diff --git a/internal/rdb/inspect.go b/internal/rdb/inspect.go
index 77cf262..242e550 100644
--- a/internal/rdb/inspect.go
+++ b/internal/rdb/inspect.go
@@ -793,31 +793,36 @@ func (r *RDB) deleteTask(key, qname, id string) error {
 }
 
 // KEYS[1] -> queue to delete
+// ARGV[1] -> task key prefix
 var deleteAllCmd = redis.NewScript(`
-local n = redis.call("ZCARD", KEYS[1])
+local ids = redis.call("ZRANGE", KEYS[1], 0, -1)
+for _, id in ipairs(ids) do
+	local key = ARGV[1] .. id
+	redis.call("DEL", key)
+end
 redis.call("DEL", KEYS[1])
-return n`)
+return table.getn(ids)`)
 
 // DeleteAllArchivedTasks deletes all archived tasks from the given queue
 // and returns the number of tasks deleted.
 func (r *RDB) DeleteAllArchivedTasks(qname string) (int64, error) {
-	return r.deleteAll(base.ArchivedKey(qname))
+	return r.deleteAll(base.ArchivedKey(qname), qname)
 }
 
 // DeleteAllRetryTasks deletes all retry tasks from the given queue
 // and returns the number of tasks deleted.
 func (r *RDB) DeleteAllRetryTasks(qname string) (int64, error) {
-	return r.deleteAll(base.RetryKey(qname))
+	return r.deleteAll(base.RetryKey(qname), qname)
 }
 
 // DeleteAllScheduledTasks deletes all scheduled tasks from the given queue
 // and returns the number of tasks deleted.
 func (r *RDB) DeleteAllScheduledTasks(qname string) (int64, error) {
-	return r.deleteAll(base.ScheduledKey(qname))
+	return r.deleteAll(base.ScheduledKey(qname), qname)
 }
 
-func (r *RDB) deleteAll(key string) (int64, error) {
-	res, err := deleteAllCmd.Run(r.client, []string{key}).Result()
+func (r *RDB) deleteAll(key, qname string) (int64, error) {
+	res, err := deleteAllCmd.Run(r.client, []string{key}, base.TaskKeyPrefix(qname)).Result()
 	if err != nil {
 		return 0, err
 	}
@@ -828,22 +833,28 @@ func (r *RDB) deleteAll(key string) (int64, error) {
 	return n, nil
 }
 
-// KEYS[1] -> asynq:{<qname>}
+// KEYS[1] -> asynq:{<qname>}:pending
+// ARGV[1] -> task key prefix
 var deleteAllPendingCmd = redis.NewScript(`
-local n = redis.call("LLEN", KEYS[1])
+local ids = redis.call("LRANGE", KEYS[1], 0, -1)
+for _, id in ipairs(ids) do
+	local key = ARGV[1] .. id
+	redis.call("DEL", key)
+end
 redis.call("DEL", KEYS[1])
-return n`)
+return table.getn(ids)`)
 
 // DeleteAllPendingTasks deletes all pending tasks from the given queue
 // and returns the number of tasks deleted.
 func (r *RDB) DeleteAllPendingTasks(qname string) (int64, error) {
-	res, err := deleteAllPendingCmd.Run(r.client, []string{base.PendingKey(qname)}).Result()
+	res, err := deleteAllPendingCmd.Run(r.client,
+		[]string{base.PendingKey(qname)}, base.TaskKeyPrefix(qname)).Result()
 	if err != nil {
 		return 0, err
 	}
 	n, ok := res.(int64)
 	if !ok {
-		return 0, fmt.Errorf("could not cast %v to int64", res)
+		return 0, fmt.Errorf("command error: unexpected return value %v", res)
 	}
 	return n, nil
 }
diff --git a/internal/rdb/inspect_test.go b/internal/rdb/inspect_test.go
index 3e9596e..16a9b2b 100644
--- a/internal/rdb/inspect_test.go
+++ b/internal/rdb/inspect_test.go
@@ -2905,6 +2905,63 @@ func TestDeleteAllScheduledTasks(t *testing.T) {
 	}
 }
 
+func TestDeleteAllPendingTasks(t *testing.T) {
+	r := setup(t)
+	defer r.Close()
+	m1 := h.NewTaskMessage("task1", nil)
+	m2 := h.NewTaskMessage("task2", nil)
+	m3 := h.NewTaskMessageWithQueue("task3", nil, "custom")
+
+	tests := []struct {
+		pending     map[string][]*base.TaskMessage
+		qname       string
+		want        int64
+		wantPending map[string][]*base.TaskMessage
+	}{
+		{
+			pending: map[string][]*base.TaskMessage{
+				"default": {m1, m2},
+				"custom":  {m3},
+			},
+			qname: "default",
+			want:  2,
+			wantPending: map[string][]*base.TaskMessage{
+				"default": {},
+				"custom":  {m3},
+			},
+		},
+		{
+			pending: map[string][]*base.TaskMessage{
+				"custom": {},
+			},
+			qname: "custom",
+			want:  0,
+			wantPending: map[string][]*base.TaskMessage{
+				"custom": {},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		h.FlushDB(t, r.client) // clean up db before each test case
+		h.SeedAllPendingQueues(t, r.client, tc.pending)
+
+		got, err := r.DeleteAllPendingTasks(tc.qname)
+		if err != nil {
+			t.Errorf("r.DeleteAllPendingTasks(%q) returned error: %v", tc.qname, err)
+		}
+		if got != tc.want {
+			t.Errorf("r.DeleteAllPendingTasks(%q) = %d, nil, want %d, nil", tc.qname, got, tc.want)
+		}
+		for qname, want := range tc.wantPending {
+			gotPending := h.GetPendingMessages(t, r.client, qname)
+			if diff := cmp.Diff(want, gotPending, h.SortMsgOpt); diff != "" {
+				t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.PendingKey(qname), diff)
+			}
+		}
+	}
+}
+
 func TestRemoveQueue(t *testing.T) {
 	r := setup(t)
 	defer r.Close()