A method of intra- and postoperative antibiotic peritoneal lavage, using 0.015% gentamicin in dialysis solution, has been assessed for the treatment of life-threatening peritonitis. It is believed to be the first time that the use of gentamicin for this purpose has been recorded, and the first time that antibiotic peritoneal lavage has been used for the treatment of a series of patients with peritonitis of gynaecological or obstetrical origin. At Baragwanath Hosital, gynaecological patients with life-threatening purulent peritonitis arising from septic abortions, tubal sepsis (ruptured pyosalpinx) or postoperative causes, were studied. Thirty-eight such patients undergoing standard operative treatment had a mortality of 47.4%, which is in accordance with world figures for serious peritonitis. In 38 patients, after the addition of antibiotic peritoneal lavage, mortality was halved to 2397%, with minimal morbidity. The procedure used has been fully described, and is recommended for wider trial in patients with life-threatening peritonitis or peritoneal soiling.