Sixteen patients with pneumaturia as their only urologic complaint were evaluated during a 38-year period. In three patients, a vesico-enteric fistula was documented. Five patients had an otherwise asymptomatic urinary tract infection. In eight patients, no pathologic process could be identified. These eight patients were women and had a benign course on follow-up. Urine culture gave positive results in all cases with a documented pathologic condition but gave negative results in all cases in which no explanation for pneumaturia could be found. Because of the difficulty in diagnosing a vesico-enteric fistula, all patients with isolated pneumaturia should have a thorough medical and urologic evaluation.