A single intramuscular dose of 500 microgram 16 phenoxy omega 17,18,19,20 tetranor PGE2 methyl sulfonylamide was used for cervical dilatation prior to vacuum aspiration in 80 first trimester nulliparae. Three hours after prostaglandin administration the cervix had dilated to 8 mm or more in 60 patients (75%). The uterus was evacuated in these patients without mechanical dilatation of the cervix. In the remaining 20 patients the cervix had dilated 4 to 7 mm. Further mechanical dilatation to 8 mm was carried out easily in most of these patients. Side effects included pain requiring analgesic (3 patients), vomiting (4 patients) and transient pyrexia (greater than 1 degrees C, 2 patients). There were no complications or damage to the uterus or the cervix during evacuation of the uterus.