Immediate breast reconstruction following mastectomy is as safe as mastectomy alone. We evaluated wound complications and potential risk factors after mastectomy with immediate breast reconstruction and compared them with similar data after modified radical mastectomy. The incidences of infection, seroma, hematoma, and epidermolysis were compared among 395 patients (305 with modified radical mastectomies and 90 with mastectomy with immediate breast reconstruction) from Virginia Mason Medical Center, Seattle, Wash, between 1983 and 1989. Obesity, age (60 years or older), smoking, antibiotics, and wound drainage were examined as possible risk factors. There were more wound complications in the modified radical mastectomy group (48% vs 31%), and specifically, more seromas (30% vs 13%). In the modified radical mastectomy group, age of 60 years or older was associated with seroma and infection, drainage greater than 30 mL per day (at time of drain removal) with seroma, and smoking with epidermolysis. In the mastectomy with immediate breast reconstruction group, obesity was associated with seroma and epidermolysis. We conclude that mastectomy with immediate breast reconstruction appears to be as safe as modified radical mastectomy alone with respect to wound complications. 