diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -377,7 +377,6 @@
 
 	if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) {
 		tp->t_srtt = rtt;
-		tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
 		TCPSTAT_INC(tcps_usedrtt);
 		if (metrics.rmx_rttvar) {
 			tp->t_rttvar = metrics.rmx_rttvar;
@@ -3634,8 +3633,6 @@
 		delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
 		if ((tp->t_rttvar += delta) <= 0)
 			tp->t_rttvar = 1;
-		if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
-		    tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	} else {
 		/*
 		 * No rtt measurement yet - use the unsmoothed rtt.
@@ -3644,7 +3641,6 @@
 		 */
 		tp->t_srtt = rtt << TCP_RTT_SHIFT;
 		tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
-		tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	}
 	tp->t_rtttime = 0;
 	tp->t_rxtshift = 0;
diff --git a/sys/netinet/tcp_stacks/bbr.c b/sys/netinet/tcp_stacks/bbr.c
--- a/sys/netinet/tcp_stacks/bbr.c
+++ b/sys/netinet/tcp_stacks/bbr.c
@@ -6384,8 +6384,6 @@
 		tp->t_rttvar += delta;
 		if (tp->t_rttvar <= 0)
 			tp->t_rttvar = 1;
-		if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
-			tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	} else {
 		/*
 		 * No rtt measurement yet - use the unsmoothed rtt. Set the
@@ -6394,7 +6392,6 @@
 		 */
 		tp->t_srtt = rtt_ticks << TCP_RTT_SHIFT;
 		tp->t_rttvar = rtt_ticks << (TCP_RTTVAR_SHIFT - 1);
-		tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	}
 	KMOD_TCPSTAT_INC(tcps_rttupdated);
 	tp->t_rttupdated++;
diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -7711,8 +7711,6 @@
 		tp->t_rttvar += (delta >> 3);
 		if (tp->t_rttvar <= 0)
 			tp->t_rttvar = 1;
-		if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
-			tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	} else {
 		/*
 		 * No rtt measurement yet - use the unsmoothed rtt. Set the
@@ -7721,7 +7719,6 @@
 		 */
 		tp->t_srtt = rtt;
 		tp->t_rttvar = rtt >> 1;
-		tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
 	}
 	rack->rc_srtt_measure_made = 1;
 	KMOD_TCPSTAT_INC(tcps_rttupdated);
diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -3131,9 +3131,8 @@
 	    tp->t_rxtcur, tp->t_maxseg, tp->t_srtt);
 
 	db_print_indent(indent);
-	db_printf("t_rttvar: %d   t_rxtshift: %d   t_rttmin: %u   "
-	    "t_rttbest: %u\n", tp->t_rttvar, tp->t_rxtshift, tp->t_rttmin,
-	    tp->t_rttbest);
+	db_printf("t_rttvar: %d   t_rxtshift: %d   t_rttmin: %u\n",
+	    tp->t_rttvar, tp->t_rxtshift, tp->t_rttmin);
 
 	db_print_indent(indent);
 	db_printf("t_rttupdated: %lu   max_sndwnd: %u   t_softerror: %d\n",
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -213,8 +213,6 @@
 	int	t_blackhole_exit;	/* when to exit blackhole detection */
 	u_int	t_rttmin;		/* minimum rtt allowed */
 
-	u_int	t_rttbest;		/* best rtt we've seen */
-
 	int	t_softerror;		/* possible error not yet reported */
 	uint32_t max_sndwnd;		/* largest window peer has offered */
 	/* Cache line 5 */