In order to evaluate that safety and effectiveness of different cannula used for the early termination of pregnancy when cervical dilatation is not required, 400 cases of early pregnancy up to 45 days since last menstrual period were selected among those who requested induced abortion at the Family Health Clinic of College of Medicine, Seoul National University and were randomly allocated to one of the four cannulas; flexible plastic cannula with one hole, flexible plastic cannula with two holes, rigid metal cannula with one hole and rigid metal cannula with two holes, for the aspiration of the uterine content with electric vacuum source. Analgesics, anestheics, and oxytocic agents were not used in all cases. After the procedure, aspirates were measured, then examined histologically for evidence of pregnancy and complications, both early and delayed, were evaluated. There was no statistically significant difference in the volume of aspirates by type of cannula and by days since last menstrual period. During the procedure and the observation period of one hour following procedure, serious early complication such as massive bleeding, uterine perforation or cervical injury was not encountered. At four-week follow-up, interview to elucidate any adverse effect perceived by patient, pelvic examination, and urine pregnancy test were performed. Folowing the procedure, 10.8 per cent of the total experienced bleeding or prolonged spotting and the frequency of bleeding complication was highest with one hole rigid cannula(24.3 per cent) and lowest with two holes flexible cannula(2.7 per cent). Suprapubic or lower abdominal cramp were reported in 10.3 per cent of the total, again the frequency being highest with one hole rigid cannula(20.3 per cent) and lowest with two holes flexible cannula(2.7 per cent). Pelvic inflammatory disease was not encountered. One patient revealed positive urine pregnancy test at four week follow-up, indicating 0.3 per cent of failure rate.