diff --git a/commands.go b/commands.go
index 300db9e..79287d5 100644
--- a/commands.go
+++ b/commands.go
@@ -359,3 +359,9 @@ func (cmd *Commands) List(channels ...string) {
 func (cmd *Commands) Whowas(user string, amount int) {
 	cmd.c.Send(&Event{Command: WHOWAS, Params: []string{user, string(amount)}})
 }
+
+// Monitor sends a MONITOR query to the server. The results of the query
+// depends on the given modifier, see https://ircv3.net/specs/core/monitor-3.2.html
+func (cmd *Commands) Monitor(modifier rune, args ...string) {
+	cmd.c.Send(&Event{Command: MONITOR, Params: append([]string{string(modifier)}, args...)})
+}
diff --git a/constants.go b/constants.go
index 58e9c15..ddb48ea 100644
--- a/constants.go
+++ b/constants.go
@@ -268,6 +268,7 @@ const (
 // IRCv3 commands and extensions :: http://ircv3.net/irc/.
 const (
 	AUTHENTICATE = "AUTHENTICATE"
+	MONITOR      = "MONITOR"
 	STARTTLS     = "STARTTLS"
 
 	CAP       = "CAP"
@@ -288,17 +289,22 @@ const (
 
 // Numeric IRC reply mapping for ircv3 :: http://ircv3.net/irc/.
 const (
-	RPL_LOGGEDIN    = "900"
-	RPL_LOGGEDOUT   = "901"
-	RPL_NICKLOCKED  = "902"
-	RPL_SASLSUCCESS = "903"
-	ERR_SASLFAIL    = "904"
-	ERR_SASLTOOLONG = "905"
-	ERR_SASLABORTED = "906"
-	ERR_SASLALREADY = "907"
-	RPL_SASLMECHS   = "908"
-	RPL_STARTTLS    = "670"
-	ERR_STARTTLS    = "691"
+	RPL_LOGGEDIN     = "900"
+	RPL_LOGGEDOUT    = "901"
+	RPL_NICKLOCKED   = "902"
+	RPL_SASLSUCCESS  = "903"
+	ERR_SASLFAIL     = "904"
+	ERR_SASLTOOLONG  = "905"
+	ERR_SASLABORTED  = "906"
+	ERR_SASLALREADY  = "907"
+	RPL_SASLMECHS    = "908"
+	RPL_STARTTLS     = "670"
+	ERR_STARTTLS     = "691"
+	RPL_MONONLINE    = "730"
+	RPL_MONOFFLINE   = "731"
+	RPL_MONLIST      = "732"
+	RPL_ENDOFMONLIST = "733"
+	ERR_MONLISTFULL  = "734"
 )
 
 // Numeric IRC event mapping :: RFC2812; section 5.3.