Objective: Severely obese patients who undergo orthotopic liver transplantation are likely to have higher morbidity, mortality, costs, and a lower long-term survival. Methods: This case-control study was done at a university hospital. One hundred twenty-one consecutive patients who underwent liver transplantation between 1994 and 1996 were studied. Severe obesity was defined as body mass index (BMI) more than 95th percentile (>32.3 for women and >31.1 for men), and moderate obesity was defined as BMI between 27.3 and 32.3 for women and 27.8 and 31.1 for men. The outcome measures were intraoperative complications, postoperative complications (wound infections, bile leak, vascular complications), length of hospital stay, costs of transplantation, and long-term survival. Results: The baseline characteristics, UNOS status, and cause of liver disease at the time of transplantation were similar in severely obese (n = 21, BMI = 37.4 ± 4.8 kg/m2), obese (n = 36, BMI 28.7 ± 0.9 kg/m2), and nonobese patients (n = 64, BMI 23.8 ± 2.5 kg/m2). The intraoperative complications and transfusion requirements were similar in all three groups. The post-operative complications such as respiratory failure (p = 0.009) and systemic vascular complications (p = 0.04) were significantly higher in severely obese patients. The overall perioperative complication rate was 0.61 (39 of 64 patients) in nonobese patients, 0.77 (28 of 36 patients) in obese patients, and 1.43 (30 of 21 patients) in severely obese patients (p = 0.01). Infections were the leading cause of death in all groups accounting for 57-66% of deaths. The length of hospital stay was significantly higher in obese patients. The hospital costs of transplantation were higher ($30,000-$40,000) in severely obese patients than in nonobese patients. The long-term patient survival was similar between the groups (Kaplan-Meier analysis). Conclusions: Despite higher postoperative complications, severely obese patients have an acceptable long-term survival, which is comparable to nonobese patients. The cost of transplantation is higher among severely obese patients. There was no increased incidence of cardiovascular mortality among severely obese patients during the follow-up period.