HYPOTHESIS: Matched patients who test positive or negative for human immunodeficiency virus (HIV) who are undergoing comparable operations have similar complication rates and outcomes. DESIGN: A retrospective study of surgical outcomes in HIV-infected and matched HIV-noninfected patients. Baseline information including HIV-related laboratory results, complications, and mortality was collected from printed and electronic records through 12 postoperative months. SETTING: Kaiser Permanente Medical Care Program-Northern California, an integrated health organization with more than 3 million members, including more than 5000 HIV-infected members. PATIENTS: From July 1,1997, through June 30, 2002, HIV-infected members undergoing surgical procedures were matched 1:1 with HIV-noninfected patients undergoing surgical procedures by type, location, and year of surgery as well as by sex and age. Surgical procedures studied included appendectomy, arthrotomy or arthroscopy, bowel resection, cholecystectomy, cardiothoracic procedures, hernia repair, hysterectomy, hip or knee replacement, laparoscopy or laparotomy, and mammoplasty. MAIN OUTCOME MEASURES: Complications and mortality through 12 postoperative months, comparisons between HIV-infected and HIV-noninfected patients using matched-pair analyses, and HIV-infected cohort data were analyzed using the Fisher exact test and logistic regression. RESULTS: Of 332 HIV-infected-HIV-noninfected pairs (mean age, 46.7 years; male sex, 91%), more than 95.0% were followed up through 12 postoperative months or until their deaths. Pairs had similar comorbidities, length of hospital stay, and number of postoperative surgical visits (P>.05, all variables). Among HIV-infected patients, the median years with HIV infection was 8.4 years; median CD4 T-cell count was 379/microL; 61.5% of these patients had an HIV RNA level less than 500 copies per milliliter; and 68% were receiving highly active antiretroviral therapy. Various complications were no more frequent among HIV-infected than in HIV-noninfected patients (11.1% vs 10.2%; P = .79), except for pneumonia (P = .04). There were more deaths within the 12 postoperative months in HIV-infected patients (10/332 vs 2/332; P = .02); 2 patients died 30 days or less after being operated on. Among HIV-infected patients, viral load of 30 000 copies per milliliter or more was associated with increased complications (adjusted odds ratio, 2.95; P = .007), but a CD4 cell count less than 200/muL was not associated with poorer outcomes. CONCLUSIONS: The HIV-infected patients had more incidences of postoperative pneumonia and higher 12-month mortality, although other operative outcomes were comparable for HIV-infected and HIV-noninfected patients. Viral suppression to fewer than 30 000 copies per milliliter reduced surgical complications.