Background. Extremes in body weight are a relative contraindication to cardiac transplantation. Methods. We retrospectively reviewed 474 consecutive adult patients (377 male, 97 female, mean age 50.3±12.2 years), who received 444 primary and 30 heart retransplants between January of 1992 and January of 1999. Of these, 68 cachectic (body mass index [BMI]<20 kg/m2), 113 overweight (BMI=>27-30 kg/m2), and 55 morbidly obese (BMI>30 kg/m2) patients were compared with 238 normal-weight recipients (BMI=20-27 kg/m2). We evaluated the influence of pretransplant BMI on morbidity and mortality after cardiac transplantation. Kaplan. Meier survival distribution and Cox proportional hazards model were used for statistical analyses. Results. Morbidly obese as well as cachectic recipients demonstrated nearly twice the 5-year mortality of normal-weight or overweight recipients (53% vs. 27%, respectively, P=0.001). An increase in mortality was seen at 30 days for morbidly obese and cachectic recipients (12.7% and 17.7%, respectively) versus a 30-day mortality rate of 7.6% in normal-weight recipients. Morbidly obese recipients experienced a shorter time to high-grade acute rejection (P=0.004) as well as an increased annual high-grade rejection frequency when compared with normal-weight recipients (P=0.001). By multivariable analysis, the incidence of transplant-related coronary artery disease (TCAD) was not increased in morbidly obese patients but cachectic patients had a significantly lower incidence of TCAD (P=0.05). Cachectic patients receiving oversized donor hearts had a significantly higher postoperative mortality (P=0.02). Conclusions. The risks of cardiac transplantation are increased in both morbidly obese and cachectic patients compared with normal-weight recipients. However, the results of cardiac transplantation in overweight patients is comparable to that in normal-weight patients. Recipient size should be kept in mind while selecting patients and the use of oversized donors in cachectic recipients should be avoided.