We have examined aspects of the anaesthetic technique that may influence the likelihood of unplanned overnight hospital admission after ambulatory gynaecological laparoscopy and have determined if any anaesthetically controllable factors were involved. The retrospective audit involved 300 patients. All patients attended the day-case unit at the Liverpool Women's Hospital between September 1996 and May 1997. One hundred ASA I-II patients who had unplanned overnight admissions during this time were evaluated. For every admitted patient, two similar patients who did not require admission were studied. Variables such as patient age and anaesthetic technique were evaluated by logistic regression. Our results indicated that postoperative emesis was the commonest cause for admission. Significant factors increasing the likelihood of unplanned admission included returning from the recovery unit after 15:00, use of a laryngeal mask airway and undergoing diagnostic laparoscopy. Significant factors reducing the likelihood of admission were the use of fentanyl and rectally administered diclofenac.