diff --git a/types/heartbeat.go b/types/heartbeat.go
new file mode 100644
index 00000000..378f6202
--- /dev/null
+++ b/types/heartbeat.go
@@ -0,0 +1,42 @@
+package types
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/tendermint/go-crypto"
+	"github.com/tendermint/go-wire"
+	"github.com/tendermint/go-wire/data"
+	cmn "github.com/tendermint/tmlibs/common"
+)
+
+type Heartbeat struct {
+	ValidatorAddress data.Bytes       `json:"validator_address"`
+	ValidatorIndex   int              `json:"validator_index"`
+	Height           int              `json:"height"`
+	Round            int              `json:"round"`
+	Sequence         int              `json:"sequence"`
+	Signature        crypto.Signature `json:"signature"`
+}
+
+func (heartbeat *Heartbeat) WriteSignBytes(chainID string, w io.Writer, n *int, err *error) {
+	wire.WriteJSON(CanonicalJSONOnceHeartbeat{
+		chainID,
+		CanonicalHeartbeat(heartbeat),
+	}, w, n, err)
+}
+
+func (heartbeat *Heartbeat) Copy() *Heartbeat {
+	heartbeatCopy := *heartbeat
+	return &heartbeatCopy
+}
+
+func (heartbeat *Heartbeat) String() string {
+	if heartbeat == nil {
+		return "nil-heartbeat"
+	}
+
+	return fmt.Sprintf("Heartbeat{%v:%X %v/%02d (%v) %v}",
+		heartbeat.ValidatorIndex, cmn.Fingerprint(heartbeat.ValidatorAddress),
+		heartbeat.Height, heartbeat.Round, heartbeat.Sequence, heartbeat.Signature)
+}