Laparoscopy is valuable in the definitive diagnosis of pelvic pain of uncertain aetiology. A clinical diagnosis of pelvic pain was made in 67 patients, but was confirmed by laparoscopy in only 34. In 36 patients in whom a clinical diagnosis of ectopic pregnancy had been made this was confirmed at laparoscopy in 21, while six of 26 positive laparoscopic diagnoses of ectopic pregnancy were unsuspected clinically. Acute pelvic inflammatory disease was diagnosed correctly on clinical grounds in only eight of 22 patients; in the other 16 patients the diagnosis was first made at laparoscopy. In these 16 patients there was poor correlation with the bacteriological results of cervical smears and cultures. Of 30 patients in whom a preoperative clinical diagnosis had not been made, laparoscopy showed normal pelvic viscera in 12. Similarly, in another eight of the 68 patients thought to have organic pelvic pathology on clinical grounds, the laparoscopic findings were normal. Apart from establishing a definitive diagnosis, laparoscopy has been found to be a safe procedure, and one of considerable cost effectiveness in terms of hospital stay.