To determine the effect of admission body weight on blunt trauma victims, a chart review of all patients greater than 12 years of age admitted to Sentara Norfolk General Hospital between January 1 and July 31, 1987 was undertaken. The charts of 351 patients were reviewed; 184 records contained admission height and weight. These 184 patients made up the study group and age, gender, injuries, Injury Severity Score (ISS), ventilator days (VD), complications, length of stay (LOS), and outcome were noted. Body Mass Index (BMI) (weight (kg)/(height(m))2, was calculated for each patient. The average ISS was 21.87 (range, 1-66) and the average BMI was 25.15 kg/m2 (range, 16-46 kg/m2). The overall mortality for the population was 9%. The population was grouped according to BMI: average (less than 27 kg/m2), overweight (27-31 kg/m2), and severely overweight (greater than 31 kg/m2). The mortality of 5.0% and 8.0% in the average and overweight groups was not different. The severely overweight group had a higher mortality at 42.1% compared with the other two groups (p less than 0.0001). The groups did not differ in age, ISS, LOS, nor VD. Age, BMI, and ISS were subjected to regression analysis. By this method BMI and ISS were independent determinants of outcome (p less than 0.0001). There was an increase in complications, mainly pulmonary problems, in the SO group (p less than 0.05). The three groups were subdivided into survivors and nonsurvivors. The nonsurvivors had a longer average LOS at 26.6 days compared with nonsurvivors in the overweight (5.0 days) or severely overweight (8.62 days) groups (p less than 0.007). The severely group was characterized by a rapid deterioration and demise that was unresponsive to intervention. ISS did not differ among nonsuvivors. Among survivors the severely overweight group had a lower ISS, 9.73. This was different from the overweight group (21.57) and from the average group (20.21) (p less than 0.04).