diff --git a/lib/ex_aws/sts.ex b/lib/ex_aws/sts.ex
index d02d721..f4c70ee 100644
--- a/lib/ex_aws/sts.ex
+++ b/lib/ex_aws/sts.ex
@@ -15,6 +15,7 @@ defmodule ExAws.STS do
           | {:token_code, binary}
           | {:external_id, binary}
           | {:policy, policy}
+          | {:tags, map}
 
   @doc """
   Assume Role.
@@ -166,5 +167,13 @@ defmodule ExAws.STS do
   defp parse_opt(opts, {:external_id, val}), do: Map.put(opts, "ExternalId", val)
   defp parse_opt(opts, {:policy, val}), do: Map.put(opts, "Policy", json_codec().encode!(val))
 
+  defp parse_opt(opts, {:tags, val}),
+    do:
+      Map.to_list(val)
+      |> Enum.with_index()
+      |> Enum.reduce(opts, fn {{k, v}, i}, acc ->
+        Map.put(acc, "Tags.member.#{i + 1}.Key", k) |> Map.put("Tags.member.#{i + 1}.Value", v)
+      end)
+
   defp json_codec(), do: ExAws.Config.build_base(:sts) |> Map.get(:json_codec)
 end