The effect of obesity on outcomes following liver transplantation remains unclear. We reviewed our experience with 302 liver transplants in 277 patients from September 1989 to September 1996 to determine the effect of body mass on outcome. Two-hundred and seventeen transplants were performed in patients with a body mass index (BMI) < 30 kg/m2, 55 in patients with a BMI of 30-34 kg/m2 (obese), and 30 in patients with a BMI > 35 kg/m2 (severely obese). Non-weight related pre-operative demographics were similar between groups with the exception of an increased frequency of cryptogenic cirrhosis among the obese and severely obese patients. Intra-operative transfusion requirements were greater for the severely obese group (16.2 +/- 3.5 units versus 9.1 +/- 0.8 units for the non-obese, p = 0.0004), though not when normalized to body weight (0.14 +/- 0.03 units/kg versus 0.13 +/- 0.01 units/kg, p > 0.05). Post-operatively, severely obese patients had a higher rate of wound infection (20 versus 4%, p = 0.0001) and death attributed to multisystem organ failure (15 versus 2%, p = 0.0001), although overall mortality prior to discharge and total complications were not different between groups. Actual 1-yr graft survival showed a negative trend in the severely obese group (67 versus 81% for non-obese, p = 0.07), but both 3-yr graft survival and patient survival were similar to non-obese patients (p = 0.12 and 0.17, respectively by the Cox-Mantel test). Liver transplantation in severely obese patients is associated with wound infection and early death from multisystem organ failure, but has similar long-term outcomes when compared to non-obese controls.