diff --git a/src/DataStructures.jl b/src/DataStructures.jl
index 9812b49ab..7c9b8013b 100644
--- a/src/DataStructures.jl
+++ b/src/DataStructures.jl
@@ -43,6 +43,8 @@ module DataStructures
     export excludelast, tokens
     export orderobject, Lt
 
+    export MultiDict, enumerateall
+
 
     if VERSION < v"0.4.0-dev"
         using Docile
@@ -68,6 +70,8 @@ module DataStructures
     include("balancedTree.jl")
     include("tokens.jl")
 
+    include("multidict.jl")
+
     import .Tokens: Token, IntSemiToken, semi, container, assemble
     import .Tokens: deref_key, deref_value, deref, status
     import .Tokens: advance, regress
diff --git a/src/multidict.jl b/src/multidict.jl
new file mode 100644
index 000000000..95392d5ab
--- /dev/null
+++ b/src/multidict.jl
@@ -0,0 +1,129 @@
+#  multi-value dictionary (multidict)
+
+import Base: haskey, get, get!, getkey, delete!, pop!, empty!,
+             setindex!, getindex, length, isempty, start,
+             next, done, keys, values, copy, similar,  push!,
+             count, size
+
+immutable MultiDict{K,V} <: Associative{K,V}
+    d::Dict{K,Vector{V}}
+
+    MultiDict() = new(Dict{K,Vector{V}}())
+    MultiDict(kvs) = new(Dict{K,Vector{V}}(kvs))
+    if VERSION >= v"0.4.0-dev+980"
+        MultiDict(ps::Pair{K,Vector{V}}...) = new(Dict{K,Vector{V}}(ps...))
+    end
+end
+
+MultiDict() = MultiDict{Any,Any}()
+MultiDict(kv::@compat Tuple{}) = MultiDict()
+MultiDict(kvs) = multi_dict_with_eltype(kvs, eltype(kvs))
+
+multi_dict_with_eltype{K,V}(kvs, ::Type{@compat Tuple{K,Vector{V}}}) = MultiDict{K,V}(kvs)
+function multi_dict_with_eltype{K,V}(kvs, ::Type{@compat Tuple{K,V}})
+    md = MultiDict{K,V}()
+    for (k,v) in kvs
+        setindex!(md, v, k)
+    end
+    return md
+end
+multi_dict_with_eltype(kvs, t) = MultiDict{Any,Any}(kvs)
+
+if VERSION >= v"0.4.0-dev+980"
+    MultiDict{K,V<:AbstractArray}(ps::Pair{K,V}...) = MultiDict{K, eltype(V)}(ps)
+    MultiDict{K,V}(kv::AbstractArray{Pair{K,V}})  = MultiDict(kv...)
+    function  MultiDict{K,V}(ps::Pair{K,V}...)
+        md = MultiDict{K,V}()
+        for (k,v) in ps
+            setindex!(md, v, k)
+        end
+        return md
+    end
+end
+
+## Functions
+
+## Most functions are simply delegated to the wrapped Dict
+
+@delegate MultiDict.d [ haskey, get, get!, getkey, delete!,
+                         empty!, getindex, length, isempty,
+                         start, next, done, keys, values ]
+
+sizehint(d::MultiDict, sz::Integer) = (sizehint(d.d, sz); d)
+copy(d::MultiDict) = MultiDict(d)
+similar{K,V}(d::MultiDict{K,V}) = MultiDict{K,V}()
+
+function setindex!{K,V}(d::MultiDict{K,V}, v, k)
+    if !haskey(d.d, k)
+        d.d[k] = isa(v, AbstractArray) ? eltype(v)[] : V[]
+    end
+    if isa(v, AbstractArray)
+        append!(d.d[k], v)
+    else
+        push!(d.d[k], v)
+    end
+    return d
+end
+
+function in{K,V}(pr::(@compat Tuple{Any,Any}), d::MultiDict{K,V})
+    k = convert(K, pr[1])
+    v = get(d,k,Base.secret_table_token)
+    !is(v, Base.secret_table_token) && (isa(pr[2], AbstractArray) ? v == pr[2] : pr[2] in v)
+end
+
+function pop!(d::MultiDict, key, default)
+    vs = get(d, key, Base.secret_table_token)
+    if is(vs, Base.secret_table_token)
+        if !is(default, Base.secret_table_token)
+            return default
+        else
+            throw(KeyError(key))
+        end
+    end
+    v = pop!(vs)
+    (length(vs) == 0) && delete!(d, key)
+    return v
+end
+pop!(d::MultiDict, key) = pop!(d, key, Base.secret_table_token)
+
+if VERSION >= v"0.4.0-dev+980"
+    push!(d::MultiDict, kv::Pair) = setindex!(d, kv[2], kv[1])
+    #push!(d::MultiDict, kv::Pair, kv2::Pair) = (push!(d.d, kv, kv2); d)
+    #push!(d::MultiDict, kv::Pair, kv2::Pair, kv3::Pair...) = (push!(d.d, kv, kv2, kv3...); d)
+end
+
+push!(d::MultiDict, kv) = setindex!(d, kv[2], kv[1])
+#push!(d::MultiDict, kv, kv2...) = (push!(d.d, kv, kv2...); d)
+
+count(d::MultiDict) = length(keys(d)) == 0 ? 0 : mapreduce(k -> length(d[k]), +, keys(d))
+size(d::MultiDict) = (length(keys(d)), count(d::MultiDict))
+
+# enumerate
+
+immutable EnumerateAll
+    d::MultiDict
+end
+enumerateall(d::MultiDict) = EnumerateAll(d)
+
+length(e::EnumerateAll) = count(e.d)
+
+function start(e::EnumerateAll)
+    V = eltype(eltype(values(e.d)))
+    vs = V[]
+    (start(e.d.d), nothing, vs, start(vs))
+end
+
+function done(e::EnumerateAll, s)
+    dst, k, vs, vst = s
+    done(vs, vst) && done(e.d.d, dst)
+end
+
+function next(e::EnumerateAll, s)
+    dst, k, vs, vst = s
+    while done(vs, vst)
+        ((k, vs), dst) = next(e.d.d, dst)
+        vst = start(vs)
+    end
+    v, vst = next(vs, vst)
+    ((k, v), (dst, k, vs, vst))
+end
\ No newline at end of file
diff --git a/test/runtests.jl b/test/runtests.jl
index f4c003878..d4eb4cbd1 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -10,7 +10,8 @@ tests = ["deque",
          "ordereddict",
          "orderedset",
          "trie",
-         "list"]
+         "list",
+         "multidict"]
 
 for t in tests
     fp = joinpath(dirname(@__FILE__), "test_$t.jl")
diff --git a/test/test_multidict.jl b/test/test_multidict.jl
new file mode 100644
index 000000000..8555e704a
--- /dev/null
+++ b/test/test_multidict.jl
@@ -0,0 +1,118 @@
+using DataStructures
+using Base.Test
+
+# construction
+KVS = ('a',[1])
+KV = ('a',1)
+@test typeof(MultiDict()) == MultiDict{Any,Any}
+@test typeof(MultiDict(())) == MultiDict{Any,Any}
+@test typeof(MultiDict([KVS])) == MultiDict{Char,Int}
+@test typeof(MultiDict([KV])) == MultiDict{Char,Int}
+@test typeof(MultiDict([KV, KVS])) == MultiDict{Char,Any}
+
+if VERSION >= v"0.4.0-dev+980"
+    PVS = 1 => [1.0]
+    PV = 1 => 1.0
+    @test eltype(MultiDict{Char,Int}()) == Tuple{Char,Int}
+    @test typeof(MultiDict(PVS)) == MultiDict{Int,Float64}
+    @test typeof(MultiDict(PVS, PVS)) == MultiDict{Int,Float64}
+    @test typeof(MultiDict([PVS, PVS])) == MultiDict{Int,Float64}
+    @test typeof(MultiDict(PV)) == MultiDict{Int,Float64}
+    @test typeof(MultiDict(PV, PV)) == MultiDict{Int,Float64}
+    @test typeof(MultiDict([PV, PV])) == MultiDict{Int,Float64}
+end
+
+# setindex!, getindex, length, isempty, empty!, in
+# copy, similar, get, haskey, getkey, start, next, done
+d = MultiDict{Char,Int}()
+
+@test length(d) == 0
+@test isempty(d)
+
+@test setindex!(d, 1, 'a') == MultiDict{Char,Int}([('a', [1])])
+@test getindex(d, 'a') == [1]
+@test setindex!(d, [2,3], 'a') == MultiDict{Char,Int}([('a', [1,2,3])])
+@test getindex(d, 'a') == [1,2,3]
+
+@test_throws KeyError d['c'] == 1
+d['c'] = 1
+@test collect(keys(d)) == ['c', 'a']
+@test collect(values(d)) == Array{Int,1}[[1],[1,2,3]]
+
+@test get(d, 'a', 0) == [1,2,3]
+@test get(d, 'b', 0) == 0
+
+@test haskey(d, 'a')
+@test !haskey(d, 'b')
+@test getkey(d, 'a', 0) == 'a'
+@test getkey(d, 'b', 0) == 0
+
+@test copy(d) == d
+@test similar(d) == MultiDict{Char,Int}()
+
+@test [kv for kv in d] == [('c',[1]), ('a',[1,2,3])]
+
+@test in(('c', 1), d)
+@test in(('a', 1), d)
+@test in(('c', [1]), d)
+@test in(('a', [1,2,3]), d)
+
+@test !isempty(d)
+empty!(d)
+@test isempty(d)
+
+# pop!
+d = MultiDict{Char,Int}([('a', [1,2,3]), ('c', [1])])
+@test_throws KeyError pop!(d, 'b')
+@test pop!(d, 'a') == 3
+@test pop!(d, 'a') == 2
+@test pop!(d, 'a') == 1
+@test !haskey(d, 'a')
+@test pop!(d, 'b', 0) == 0
+
+# delete!
+d = MultiDict{Char,Int}([('a', [1,2,3]), ('c', [1])])
+@test delete!(d, 'b') == d
+@test delete!(d, 'a') == MultiDict{Char,Int}([('c', [1])])
+
+# setindex!
+d = MultiDict{Char,Int}()
+@test setindex!(d, 1, 'a') == MultiDict{Char,Int}([('a', [1])])
+@test setindex!(d, 1, 'a') == MultiDict{Char,Int}([('a', [1, 1])])
+
+# push!
+d = MultiDict{Char,Int}()
+@test push!(d, ('a',[1])) == MultiDict{Char,Int}([('a', [1])])
+@test push!(d, ('a',[1])) == MultiDict{Char,Int}([('a', [1,1])])
+empty!(d)
+@test push!(d, ('a',1)) == MultiDict{Char,Int}([('a', [1])])
+@test push!(d, ('a',1)) == MultiDict{Char,Int}([('a', [1,1])])
+
+if VERSION >= v"0.4.0-dev+980"
+    empty!(d)
+    @test push!(d,'a'=>[1]) == MultiDict{Char,Int}([('a', [1])])
+    @test push!(d, 'a'=>1) == MultiDict{Char,Int}([('a', [1,1])])
+end
+
+# get!
+@test get!(d, 'a', []) == [1,1]
+@test get!(d, 'b', []) == Int[]
+@test get!(d, 'c', [1]) == [1]
+@test_throws MethodError get!(d, 'd', 1)
+
+# special functions: count, enumerateall
+d = MultiDict{Char,Int}()
+@test count(d) == 0
+for i in 1:15
+    d[rand('a':'f')] = rand()>0.5 ? rand(1:10) : rand(1:10, rand(1:3))
+end
+@test 15 <= count(d) <=45
+@test size(d) == (length(d), count(d))
+
+allvals = [kv for kv in enumerateall(d)]
+@test length(allvals) == count(d)
+@test all([in(kv,d) for kv in enumerateall(d)])
+
+# @test length(d) == 15
+# @test length(values(d)) == 15
+# @test length(keys(d)) <= 6