diff --git a/app/vmalert/group.go b/app/vmalert/group.go
index d89f5037c3..3009a76507 100644
--- a/app/vmalert/group.go
+++ b/app/vmalert/group.go
@@ -303,6 +303,10 @@ func (g *Group) start(ctx context.Context, nts func() []notifier.Notifier, rw *r
 				g.mu.Unlock()
 				continue
 			}
+
+			// ensure that staleness is tracked or existing rules only
+			e.purgeStaleSeries(g.Rules)
+
 			if g.Interval != ng.Interval {
 				g.Interval = ng.Interval
 				t.Stop()
@@ -457,6 +461,30 @@ func (e *executor) getStaleSeries(rule Rule, tss []prompbmarshal.TimeSeries, tim
 	return staleS
 }
 
+// purgeStaleSeries deletes references in tracked
+// previouslySentSeriesToRW list to Rules which aren't present
+// in the given activeRules list. The method is used when the list
+// of loaded rules has changed and executor has to remove
+// references to non-existing rules.
+func (e *executor) purgeStaleSeries(activeRules []Rule) {
+	newPreviouslySentSeriesToRW := make(map[uint64]map[string][]prompbmarshal.Label)
+
+	e.previouslySentSeriesToRWMu.Lock()
+
+	for _, rule := range activeRules {
+		id := rule.ID()
+		prev, ok := e.previouslySentSeriesToRW[id]
+		if ok {
+			// keep previous series for staleness detection
+			newPreviouslySentSeriesToRW[id] = prev
+		}
+	}
+	e.previouslySentSeriesToRW = nil
+	e.previouslySentSeriesToRW = newPreviouslySentSeriesToRW
+
+	e.previouslySentSeriesToRWMu.Unlock()
+}
+
 func labelsToString(labels []prompbmarshal.Label) string {
 	var b strings.Builder
 	b.WriteRune('{')
diff --git a/app/vmalert/group_test.go b/app/vmalert/group_test.go
index 8322e65d02..ab2cfe9511 100644
--- a/app/vmalert/group_test.go
+++ b/app/vmalert/group_test.go
@@ -355,3 +355,61 @@ func TestGetStaleSeries(t *testing.T) {
 		[][]prompbmarshal.Label{toPromLabels(t, "__name__", "job:foo", "job", "bar")},
 		nil)
 }
+
+func TestPurgeStaleSeries(t *testing.T) {
+	ts := time.Now()
+	labels := toPromLabels(t, "__name__", "job:foo", "job", "foo")
+	tss := []prompbmarshal.TimeSeries{newTimeSeriesPB([]float64{1}, []int64{ts.Unix()}, labels)}
+
+	f := func(curRules, newRules, expStaleRules []Rule) {
+		t.Helper()
+		e := &executor{
+			previouslySentSeriesToRW: make(map[uint64]map[string][]prompbmarshal.Label),
+		}
+		// seed executor with series for
+		// current rules
+		for _, rule := range curRules {
+			e.getStaleSeries(rule, tss, ts)
+		}
+
+		e.purgeStaleSeries(newRules)
+
+		if len(e.previouslySentSeriesToRW) != len(expStaleRules) {
+			t.Fatalf("expected to get %d stale series, got %d",
+				len(expStaleRules), len(e.previouslySentSeriesToRW))
+		}
+
+		for _, exp := range expStaleRules {
+			if _, ok := e.previouslySentSeriesToRW[exp.ID()]; !ok {
+				t.Fatalf("expected to have rule %d; got nil instead", exp.ID())
+			}
+		}
+	}
+
+	f(nil, nil, nil)
+	f(
+		nil,
+		[]Rule{&AlertingRule{RuleID: 1}},
+		nil,
+	)
+	f(
+		[]Rule{&AlertingRule{RuleID: 1}},
+		nil,
+		nil,
+	)
+	f(
+		[]Rule{&AlertingRule{RuleID: 1}},
+		[]Rule{&AlertingRule{RuleID: 2}},
+		nil,
+	)
+	f(
+		[]Rule{&AlertingRule{RuleID: 1}, &AlertingRule{RuleID: 2}},
+		[]Rule{&AlertingRule{RuleID: 2}},
+		[]Rule{&AlertingRule{RuleID: 2}},
+	)
+	f(
+		[]Rule{&AlertingRule{RuleID: 1}, &AlertingRule{RuleID: 2}},
+		[]Rule{&AlertingRule{RuleID: 1}, &AlertingRule{RuleID: 2}},
+		[]Rule{&AlertingRule{RuleID: 1}, &AlertingRule{RuleID: 2}},
+	)
+}