Thromboembolism is a serious complication of surgery and prophylaxis is therefore recommended. This study examines a new aspect of the problem, the incidence of thromboembolism after day-case surgery. From 1982 to 1992, 2281 patients underwent day-case repair for inguinal hernia management. Hospital admission for thromboembolism within the first 30 days after surgery was identified by computer linkage to the National In-Patient register, which contains details of all hospital admissions in Denmark. One patient developed non-fatal pulmonary embolism. No other patients were admitted to hospital with venous thromboembolism within 30 days of herniorrhaphy. It is concluded that there is no need for routine prophylaxis for thromboembolism in day-case hernia surgery.