We attempted to show that surgical treatment of breast cancer, including axillary lymph node dissection with or without concomitant partial mastectomy (ALND), simple mastectomy (SM), and modified radical mastectomy (MRM) can be performed safely in an outpatient setting. The records of 100 consecutive women undergoing definitive breast cancer surgery by the authors between August 1994 and July 1996 were retrospectively reviewed. Average age was 54 +/- 10 years. Fifty patients were discharged the day of surgery, 44 were hospitalized, and 6 remained 2 or more days postoperatively. Outpatients were more likely to have undergone ALND or SM (42 versus 23 procedures) and more often completed surgery in the morning (36 versus 12); P < 0.05. Eight patients of 35 with MRM were discharged the same day. One patient was readmitted with a wound infection. There were no major complications or deaths. Ninety-four per cent of patients were discharged within 23 hours of surgery; half were discharged the same day. No complications occurred in outpatients, and there were no readmissions. For patients admitted overnight, no complications were detected during the overnight hospital stay. In conclusion, breast cancer surgery, from ALND to SM or MRM, can be safely and comfortably performed on an outpatient basis.