diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.2
+
+* Optimize the `insertMany` function to insert all rows and retrieve their keys in one SQL query. [#407](https://github.com/yesodweb/persistent/pull/407)
+
 ## 2.1.6
 
 * Postgresql exceptions [#353](https://github.com/yesodweb/persistent/issues/353)
diff --git a/Database/Persist/Postgresql.hs b/Database/Persist/Postgresql.hs
--- a/Database/Persist/Postgresql.hs
+++ b/Database/Persist/Postgresql.hs
@@ -147,6 +147,7 @@
         { connPrepare    = prepare' conn
         , connStmtMap    = smap
         , connInsertSql  = insertSql'
+        , connInsertManySql = Just insertManySql'
         , connClose      = PG.close conn
         , connMigrateSql = migrate'
         , connBegin      = const $ PG.begin    conn
@@ -187,6 +188,21 @@
   in case entityPrimary ent of
        Just _pdef -> ISRManyKeys sql vals
        Nothing -> ISRSingle (sql <> " RETURNING " <> escape (fieldDB (entityId ent)))
+
+-- | SQL for inserting multiple rows at once and returning their primary keys.
+insertManySql' :: EntityDef -> [[PersistValue]] -> InsertSqlResult
+insertManySql' ent valss =
+  let sql = T.concat
+                [ "INSERT INTO "
+                , escape (entityDB ent)
+                , "("
+                , T.intercalate "," $ map (escape . fieldDB) $ entityFields ent
+                , ") VALUES ("
+                , T.intercalate "),(" $ replicate (length valss) $ T.intercalate "," $ map (const "?") (entityFields ent)
+                , ") RETURNING "
+                , T.intercalate ", " $ dbIdColumnsEsc escape ent
+                ]
+  in ISRSingle sql
 
 execute' :: PG.Connection -> PG.Query -> [PersistValue] -> IO Int64
 execute' conn query vals = PG.execute conn query (map P vals)
diff --git a/persistent-postgresql.cabal b/persistent-postgresql.cabal
--- a/persistent-postgresql.cabal
+++ b/persistent-postgresql.cabal
@@ -1,5 +1,5 @@
 name:            persistent-postgresql
-version:         2.1.6
+version:         2.2
 license:         MIT
 license-file:    LICENSE
 author:          Felipe Lessa, Michael Snoyman <michael@snoyman.com>
@@ -19,7 +19,7 @@
                    , transformers          >= 0.2.1
                    , postgresql-simple     >= 0.4.0    && < 0.5
                    , postgresql-libpq      >= 0.6.1    && < 0.10
-                   , persistent            >= 2.1.5    && < 3
+                   , persistent            >= 2.2      && < 3
                    , containers            >= 0.2
                    , bytestring            >= 0.9
                    , text                  >= 0.7