diff --git a/DESCRIPTION b/DESCRIPTION
index ca21590c..02de5e3e 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: simtrial
 Type: Package
 Title: Clinical Trial Simulation
-Version: 0.3.2.10
+Version: 0.3.2.11
 Authors@R: c(
     person("Keaven", "Anderson", email = "keaven_anderson@merck.com", role = c("aut")),
     person("Yilong", "Zhang", email = "elong0527@gmail.com", role =  c("aut")),
diff --git a/NAMESPACE b/NAMESPACE
index 4f6b6de3..c818fb50 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -20,6 +20,7 @@ export(multitest)
 export(pvalue_maxcombo)
 export(randomize_by_fixed_block)
 export(rmst)
+export(rmst.formula)
 export(rpwexp)
 export(rpwexp_enroll)
 export(sim_fixed_n)
diff --git a/R/rmst.R b/R/rmst.R
index 8e4cfb86..7e37dd7a 100644
--- a/R/rmst.R
+++ b/R/rmst.R
@@ -299,3 +299,26 @@ rmst_single_arm <- function(
 
   return(ans)
 }
+
+#' @export
+rmst.formula <- function(formula, data, tau = 10, reference = "control",
+                         alpha = 0.05) {
+  stopifnot(is.data.frame(data))
+
+  variables <- colnames(stats::get_all_vars(formula = formula, data = data))
+  if (length(variables) != 3) {
+    stop("The formula interface requires exactly 3 variables specified")
+  }
+
+  ans <- rmst(
+    data = data,
+    tau = tau,
+    var_label_tte = variables[1],
+    var_label_event = variables[2],
+    var_label_group = variables[3],
+    reference = reference,
+    alpha = alpha
+  )
+
+  return(ans)
+}
diff --git a/tests/testthat/test-unvalidated-rmst.R b/tests/testthat/test-unvalidated-rmst.R
new file mode 100644
index 00000000..1a199d0f
--- /dev/null
+++ b/tests/testthat/test-unvalidated-rmst.R
@@ -0,0 +1,47 @@
+test_that("rmst() snapshot test", {
+  data(ex1_delayed_effect)
+  observed <- rmst(
+    data = ex1_delayed_effect,
+    var_label_tte = "month",
+    var_label_event = "evntd",
+    var_label_group = "trt",
+    tau = 10,
+    reference = "0"
+  )
+  expected <- data.frame(
+    rmst_arm1 = 6.495175253205431,
+    rmst_arm0 = 5.630125973237457,
+    rmst_diff = 0.8650492799679741,
+    z = 2.2178796367487963
+  )
+  expect_equal(observed, expected)
+})
+
+test_that("formula method matches default method", {
+  data(ex1_delayed_effect)
+
+  rmst_default <- rmst(
+    data = ex1_delayed_effect,
+    var_label_tte = "month",
+    var_label_event = "evntd",
+    var_label_group = "trt",
+    tau = 10,
+    reference = "0"
+  )
+
+  rmst_formula_1 <- rmst.formula(
+    month ~ evntd + trt,
+    data = ex1_delayed_effect,
+    tau = 10,
+    reference = "0"
+  )
+  expect_equal(rmst_formula_1, rmst_default)
+
+  rmst_formula_2 <- rmst.formula(
+    survival::Surv(month | evntd) ~ trt,
+    data = ex1_delayed_effect,
+    tau = 10,
+    reference = "0"
+  )
+  expect_equal(rmst_formula_2, rmst_default)
+})