OBJECTIVE: To determine the morbidity of abdominal hysterectomy. DESIGN: Descriptive. Physician billings to the Quebec Health Care Plan in the 1-month period after abdominal hysterectomy were examined. SETTING: Operations performed in 102 hospitals in the Province of Quebec between Jan. 1, 1989, and Mar. 31, 1989, were selected. PATIENTS: The study group included 3322 patients who had abdominal hysterectomy. Patients who had vaginal or abdominal hysterectomy for invasive cancer or pregnancy-related complications were excluded. A patient was considered to be morbid if the physician's intervention indicated concern for the patient's well-being. MAIN OUTCOME MEASURES: Multiple logistic regression analysis to determine the adjusted rate ratio for inclusion in a categorical list of morbid patients among different subsets of surgeons, hospitals and patients. RESULTS: Postoperative morbidity occurred in 646 patients (19.5%), who spent an average of 1.7 days longer in the hospital than patients with no postoperative morbidity. There were two postoperative deaths (0.1%). Forty-nine patients (1.5%) had postoperative surgical intervention. On 119 occasions (3.6%), patients were treated in the intensive care unit. A consultation was given by a medical specialist in 303 cases (9.1%). The rate ratio for postoperative morbidity was not significantly affected by years in practice or specialty of the surgeon but was increased for operations performed in mid-sized hospitals. The strongest predictor of postoperative morbidity was pre-existing medical disorder (RR). CONCLUSION: The major causes of morbidity in patients who undergo abdominal hysterectomies are medical rather than surgical.