A retrospective clinical study of acute and persistent diarrhea in children younger than three years of age was conducted for 12 months (October 1989 to September 1990) in a Pediatric Hospital in Ho Chi Minh City, South Vietnam. Most of the 3833 episodes of diarrhea identified were of short duration, with 77.7% lasting only 1-7 days. Only 5.3% of episodes lasted more than 14 days. Episodes of longer duration were associated with young age (0-5 months). Bloody stool was present in more than 40% of persistent episodes. Severe malnutrition was associated with persistent episodes that lasted 14-21 days (33%) or more than 22 days (59%). It is important that all patients with diarrhea have appropriate dietary management in addition to fluid therapy, and that future analysis examines etiologic factors to determine the optimal treatment of bloody diarrhea.