Preliminary results of a retrospective study of 773 cases of hysteroscopic sterilization are presented. Of the 524 cases tested for tubal patency, 186 (35.5%) were considered failures either because of incomplete blockage of the tubes or pregnancy. Fifty-nine pregnancies (23.7%) were reported in the 249 cases which were not tested for tubal patency. In the total population 25 complications were designated as major, for a major complication rate of 3.2%. These included uterine perforation, bowel damage, peritonitis, ectopic pregnancy, and 1 death from bowel perforation with peritonitis. The implications of these excessively high failure and complication rates are discussed, and plans are described for further analysis of the data.