diff --git a/PENDING.md b/PENDING.md
index c370c0a96e..0012b26f50 100644
--- a/PENDING.md
+++ b/PENDING.md
@@ -34,11 +34,12 @@ IMPROVEMENTS
 * Gaia
 
 * SDK
+  * [\#3601] JSON-stringify the ABCI log response which includes the log and message
+  index.
   * [\#3604] Improve SDK funds related error messages and allow for unicode in
   JSON ABCI log.
   * [\#3620](https://github.com/cosmos/cosmos-sdk/pull/3620) Version command shows build tags
-
-  * \#3638 Add Bcrypt benchmarks & justification of security parameter choice
+  * [\#3638] Add Bcrypt benchmarks & justification of security parameter choice
 
 * Tendermint
   * [\#3618] Upgrade to Tendermint 0.30.03
diff --git a/baseapp/baseapp.go b/baseapp/baseapp.go
index c7f7cda868..3b61342c8b 100644
--- a/baseapp/baseapp.go
+++ b/baseapp/baseapp.go
@@ -628,9 +628,15 @@ func (app *BaseApp) getContextForTx(mode runTxMode, txBytes []byte) (ctx sdk.Con
 	return
 }
 
+type indexedABCILog struct {
+	MsgIndex int    `json:"msg_index"`
+	Success  bool   `json:"success"`
+	Log      string `json:"log"`
+}
+
 // runMsgs iterates through all the messages and executes them.
 func (app *BaseApp) runMsgs(ctx sdk.Context, msgs []sdk.Msg, mode runTxMode) (result sdk.Result) {
-	logs := make([]string, 0, len(msgs))
+	idxlogs := make([]indexedABCILog, 0, len(msgs)) // a list of JSON-encoded logs with msg index
 
 	var data []byte   // NOTE: we just append them all (?!)
 	var tags sdk.Tags // also just append them all
@@ -659,23 +665,28 @@ func (app *BaseApp) runMsgs(ctx sdk.Context, msgs []sdk.Msg, mode runTxMode) (re
 		tags = append(tags, sdk.MakeTag(sdk.TagAction, msg.Type()))
 		tags = append(tags, msgResult.Tags...)
 
+		idxLog := indexedABCILog{MsgIndex: msgIdx, Log: msgResult.Log}
+
 		// stop execution and return on first failed message
 		if !msgResult.IsOK() {
-			logs = append(logs, fmt.Sprintf("Msg %d failed: %s", msgIdx, msgResult.Log))
+			idxLog.Success = false
+			idxlogs = append(idxlogs, idxLog)
+
 			code = msgResult.Code
 			codespace = msgResult.Codespace
 			break
 		}
 
-		// construct usable logs in multi-message transactions
-		logs = append(logs, fmt.Sprintf("Msg %d: %s", msgIdx, msgResult.Log))
+		idxLog.Success = true
+		idxlogs = append(idxlogs, idxLog)
 	}
 
+	logJSON := codec.Cdc.MustMarshalJSON(idxlogs)
 	result = sdk.Result{
 		Code:      code,
 		Codespace: codespace,
 		Data:      data,
-		Log:       strings.Join(logs, "\n"),
+		Log:       strings.TrimSpace(string(logJSON)),
 		GasUsed:   ctx.GasMeter().GasConsumed(),
 		Tags:      tags,
 	}