Nonoperative management of blunt trauma involving the liver and spleen has been accepted in stable pediatric patients but has been controversial in adult patients. The purpose of this study was to compare nonoperative management of blunt liver and spleen injuries in adult patients with a similar group of adult patients treated operatively and with a group of pediatric patients treated nonoperatively. A 5-year retrospective study was carried out on all hemodynamically stable patients who came to our institution with blunt abdominal trauma. There were 20 adults treated operatively (group I), 25 adults treated nonoperatively (group II), and 34 pediatric patients treated nonoperatively (group III). The mean acute physiology and chronic health evaluation score for group I was 5.1; group II, 3.1; and group III, 7.9. Delayed splenectomy was required in four adult patients in group I and in one patient in group III. There were no deaths. The mean total blood requirement was 6.0 units for group I, 2.8 units for group II, and 1.7 units for group III. The average hospital stay was 19.1 days for group I, 12.6 days for group II, and 9.2 days for group III. These data suggest that the outcome of adult patients whose blunt liver and spleen injuries are managed nonoperatively is comparable with that of pediatric patients treated nonoperatively and is as good as that of adults undergoing early laparotomy.