diff --git a/cloud/gcp/cloud-sql/mysql/README.md b/cloud/gcp/cloud-sql/mysql/README.md
index 1d0cecd..d316646 100644
--- a/cloud/gcp/cloud-sql/mysql/README.md
+++ b/cloud/gcp/cloud-sql/mysql/README.md
@@ -29,6 +29,7 @@ Useful links
 * [GCP Metrics for CloudSQL](https://cloud.google.com/monitoring/api/metrics_gcp#gcp-cloudsql)
 * [Datadog Useful monitors for GCP CloudSQL](https://www.datadoghq.com/blog/monitor-google-cloud-sql/)
 * [Max connections depends on the type of the instance](https://cloud.google.com/sql/docs/quotas#fixed-limits)
+* [Monitoring Replication Lag](https://cloud.google.com/sql/docs/mysql/high-availability#replication-lag-monitor)
 
 Inputs
 ------
@@ -47,3 +48,8 @@ Inputs
 | network_connections_threshold_warning | Number of network connections (warning threshold) | string | `3200` | no |
 | network_connections_timeframe | Timeframe for the Network Connections monitor | string | `last_5m` | no |
 | project_id | ID of the GCP Project | string | - | yes |
+| replication_lag_message | Custom message for the Replication Lag monitor | string | `` | no |
+| replication_lag_silenced | Groups to mute for GCP Cloud SQL Replication Lag monitor | map | `<map>` | no |
+| replication_lag_threshold_critical | Seconds behind the master (critical threshold) | string | `2700` | no |
+| replication_lag_threshold_warning | Seconds behind the master (warning threshold) | string | `2000` | no |
+| replication_lag_timeframe | Timeframe for the Replication Lag monitor | string | `last_10m` | no |
diff --git a/cloud/gcp/cloud-sql/mysql/inputs.tf b/cloud/gcp/cloud-sql/mysql/inputs.tf
index b1fbc95..65f190e 100644
--- a/cloud/gcp/cloud-sql/mysql/inputs.tf
+++ b/cloud/gcp/cloud-sql/mysql/inputs.tf
@@ -71,3 +71,36 @@ variable "network_connections_silenced" {
   type        = "map"
   default     = {}
 }
+
+#
+# Replication Lag
+#
+variable "replication_lag_message" {
+  description = "Custom message for the Replication Lag monitor"
+  type        = "string"
+  default     = ""
+}
+
+variable "replication_lag_timeframe" {
+  description = "Timeframe for the Replication Lag monitor"
+  type        = "string"
+  default     = "last_10m"
+}
+
+variable "replication_lag_threshold_warning" {
+  description = "Seconds behind the master (warning threshold)"
+  type        = "string"
+  default     = 2000
+}
+
+variable "replication_lag_threshold_critical" {
+  description = "Seconds behind the master (critical threshold)"
+  type        = "string"
+  default     = 2700
+}
+
+variable "replication_lag_silenced" {
+  description = "Groups to mute for GCP Cloud SQL Replication Lag monitor"
+  type        = "map"
+  default     = {}
+}
diff --git a/cloud/gcp/cloud-sql/mysql/monitors-cloudsql-mysql.tf b/cloud/gcp/cloud-sql/mysql/monitors-cloudsql-mysql.tf
index 847de67..8c4a580 100644
--- a/cloud/gcp/cloud-sql/mysql/monitors-cloudsql-mysql.tf
+++ b/cloud/gcp/cloud-sql/mysql/monitors-cloudsql-mysql.tf
@@ -52,3 +52,45 @@ EOF
     "engine:mysql",
   ]
 }
+
+#
+# Replication Lag
+#
+resource "datadog_monitor" "datadog_monitor_cloud_sql_mysql_replication_lag" {
+  name    = "[${var.environment}] Cloud SQL MySQL Replication Lag too high"
+  message = "${coalesce(var.replication_lag_message, var.message)}"
+
+  type = "metric alert"
+
+  query = <<EOF
+    min(last_10m):
+      avg:gcp.cloudsql.database.mysql.replication.seconds_behind_master{${data.template_file.filter.rendered}}
+      by {database_id}
+      > ${var.replication_lag_threshold_critical}
+EOF
+
+  thresholds {
+    critical = "${var.replication_lag_threshold_critical}"
+    warning  = "${var.replication_lag_threshold_warning}"
+  }
+
+  include_tags        = true
+  notify_no_data      = true
+  require_full_window = false
+  renotify_interval   = 0
+  notify_audit        = false
+  timeout_h           = 0
+  include_tags        = true
+  locked              = false
+  evaluation_delay    = "${var.delay}"
+  new_host_delay      = "${var.delay}"
+  silenced            = "${var.questions_changing_silenced}"
+
+  tags = [
+    "team:gcp",
+    "provider:gcp",
+    "env:${var.environment}",
+    "resource:cloud-sql",
+    "engine:mysql",
+  ]
+}