diff --git a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/common/Slices.scala b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/common/Slices.scala
new file mode 100644
index 000000000..cb713c357
--- /dev/null
+++ b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/common/Slices.scala
@@ -0,0 +1,6 @@
+package com.sksamuel.elastic4s.requests.common
+
+sealed trait Slices
+
+case object AutoSlices extends Slices
+case class NumericSlices(slices: Int) extends Slices
diff --git a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryAsyncRequest.scala b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryAsyncRequest.scala
index f6cf9df5d..759dcbee3 100644
--- a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryAsyncRequest.scala
+++ b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryAsyncRequest.scala
@@ -2,7 +2,7 @@ package com.sksamuel.elastic4s.requests.update
 
 import com.sksamuel.elastic4s.Indexes
 import com.sksamuel.elastic4s.ext.OptionImplicits._
-import com.sksamuel.elastic4s.requests.common.{RefreshPolicy, Slice}
+import com.sksamuel.elastic4s.requests.common.{AutoSlices, NumericSlices, RefreshPolicy, Slice, Slices}
 import com.sksamuel.elastic4s.requests.script.Script
 import com.sksamuel.elastic4s.requests.searches.queries.Query
 
@@ -20,7 +20,7 @@ case class UpdateByQueryAsyncRequest(indexes: Indexes,
                                      retryBackoffInitialTime: Option[FiniteDuration] = None,
                                      scroll: Option[String] = None,
                                      scrollSize: Option[Int] = None,
-                                     slices: Option[Int] = None,
+                                     slices: Option[Slices] = None,
                                      slice: Option[Slice] = None,
                                      timeout: Option[FiniteDuration] = None,
                                      shouldStoreResult: Option[Boolean] = None,
@@ -40,7 +40,8 @@ case class UpdateByQueryAsyncRequest(indexes: Indexes,
 
   def scrollSize(scrollSize: Int): UpdateByQueryAsyncRequest = copy(scrollSize = scrollSize.some)
   def slice(slice: Slice): UpdateByQueryAsyncRequest = copy(slice = slice.some)
-  def slices(slices: Int): UpdateByQueryAsyncRequest = copy(slices = slices.some)
+  def slices(slices: Int): UpdateByQueryAsyncRequest = copy(slices = Some(NumericSlices(slices)))
+  def slicesAuto(): UpdateByQueryAsyncRequest = copy(slices = Some(AutoSlices))
 
   def requestsPerSecond(requestsPerSecond: Float): UpdateByQueryAsyncRequest =
     copy(requestsPerSecond = requestsPerSecond.some)
diff --git a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryRequest.scala b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryRequest.scala
index b9b5122eb..7deaf1a19 100644
--- a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryRequest.scala
+++ b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryRequest.scala
@@ -1,7 +1,7 @@
 package com.sksamuel.elastic4s.requests.update
 
 import com.sksamuel.elastic4s.Indexes
-import com.sksamuel.elastic4s.requests.common.{RefreshPolicy, Slice}
+import com.sksamuel.elastic4s.requests.common.{ AutoSlices, NumericSlices, RefreshPolicy, Slice, Slices}
 import com.sksamuel.elastic4s.requests.script.Script
 import com.sksamuel.elastic4s.requests.searches.queries.Query
 import com.sksamuel.elastic4s.ext.OptionImplicits._
@@ -33,7 +33,7 @@ trait BaseUpdateByQueryRequest {
 
   val scrollSize: Option[Int]
 
-  val slices: Option[Int]
+  val slices: Option[Slices]
 
   val slice: Option[Slice]
 
@@ -59,7 +59,7 @@ case class UpdateByQueryRequest(indexes: Indexes,
                                 retryBackoffInitialTime: Option[FiniteDuration] = None,
                                 scroll: Option[String] = None,
                                 scrollSize: Option[Int] = None,
-                                slices: Option[Int] = None,
+                                slices: Option[Slices] = None,
                                 slice: Option[Slice] = None,
                                 timeout: Option[FiniteDuration] = None,
                                 shouldStoreResult: Option[Boolean] = None,
@@ -79,7 +79,8 @@ case class UpdateByQueryRequest(indexes: Indexes,
 
   def scrollSize(scrollSize: Int): UpdateByQueryRequest = copy(scrollSize = scrollSize.some)
   def slice(slice: Slice): UpdateByQueryRequest = copy(slice = slice.some)
-  def slices(slices: Int): UpdateByQueryRequest = copy(slices = slices.some)
+  def slices(slices: Int): UpdateByQueryRequest = copy(slices = Some(NumericSlices(slices)))
+  def slicesAuto(): UpdateByQueryRequest = copy(slices = Some(AutoSlices))
 
   def requestsPerSecond(requestsPerSecond: Float): UpdateByQueryRequest =
     copy(requestsPerSecond = requestsPerSecond.some)
diff --git a/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/update/UpdateHandlers.scala b/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/update/UpdateHandlers.scala
index 08709907a..33a90e2e4 100644
--- a/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/update/UpdateHandlers.scala
+++ b/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/update/UpdateHandlers.scala
@@ -6,7 +6,7 @@ import com.sksamuel.elastic4s.handlers.common.FetchSourceContextQueryParameterFn
 import com.sksamuel.elastic4s.handlers.script.ScriptBuilderFn
 import com.sksamuel.elastic4s.handlers.searches.queries
 import com.sksamuel.elastic4s.json.{XContentBuilder, XContentFactory}
-import com.sksamuel.elastic4s.requests.common.RefreshPolicyHttpValue
+import com.sksamuel.elastic4s.requests.common.{AutoSlices, NumericSlices, RefreshPolicyHttpValue}
 import com.sksamuel.elastic4s.requests.task.GetTask
 import com.sksamuel.elastic4s.requests.update.{BaseUpdateByQueryRequest, UpdateByQueryAsyncRequest, UpdateByQueryAsyncResponse, UpdateByQueryRequest, UpdateByQueryResponse, UpdateByQueryTask, UpdateRequest, UpdateResponse}
 import com.sksamuel.elastic4s.{BulkIndexByScrollFailure, ElasticError, ElasticRequest, ElasticUrlEncoder, Handler, HttpEntity, HttpResponse, ResponseHandler}
@@ -87,7 +87,10 @@ trait UpdateHandlers {
       request.scrollSize.foreach(params.put("scroll_size", _))
       request.waitForActiveShards.foreach(params.put("wait_for_active_shards", _))
       request.waitForCompletion.foreach(params.put("wait_for_completion", _))
-      request.slices.foreach(params.put("slices", _))
+      request.slices.foreach {
+        case AutoSlices            => params.put("slices", "auto")
+        case NumericSlices(slices) => params.put("slices", slices)
+      }
 
       val body = UpdateByQueryBodyFn(request)
       logger.debug(s"Update by query ${body.string}")
diff --git a/elastic4s-tests/src/test/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryTest.scala b/elastic4s-tests/src/test/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryTest.scala
index 808bf9e8d..7fc7ae2ef 100644
--- a/elastic4s-tests/src/test/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryTest.scala
+++ b/elastic4s-tests/src/test/scala/com/sksamuel/elastic4s/requests/update/UpdateByQueryTest.scala
@@ -65,6 +65,16 @@ class UpdateByQueryTest
     }.await.result.count shouldBe 3
   }
 
+  it should "support slices auto" in {
+    client.execute {
+      updateByQuery("pop", matchAllQuery()).script(script("ctx._source.foo = 'd'").lang("painless")).slicesAuto().refresh(RefreshPolicy.IMMEDIATE)
+    }.await.result.updated shouldBe 3
+
+    client.execute {
+      count("pop").query(termQuery("foo", "d"))
+    }.await.result.count shouldBe 3
+  }
+  
   it should "support RefreshPolicy.NONE" in {
     client.execute {
       updateByQuery("pop", matchAllQuery()).script(script("ctx._source.foo = 'c'").lang("painless")).refresh(RefreshPolicy.NONE)