Preoperative dilatation of the cervix at first trimester legal abortion has been shown to facilitate the vacuum aspiration procedure and to reduce per- and postoperative complications as well as late sequelae. The present study represents a clinical trial in which a new synthetic hygroscopic tent, Dilapan, has been evaluated. Dilapan tents of different diameters with different durations of cervical exposure were tested on a case material of 450 nulliparous women. It was found that treatment with 4 mm tents during 3-4 h or 3 mm tents during 16-20 h produced a cervical dilatation that allowed an easy evacuation of the uterus with a minimum of complications. The advantage of this particular tent is its property of rapid swelling.