Duplications of the intestinal tract are rare malformations, and triplications are even less frequent; only two cases are found in the literature. Peritoneal melanosis, a diffuse, black pigmentation of the peritoneum is also rare; only six cases have been reported; five in young women and one in a 2-year-old girl. The authors report on a 6-month-old boy with a gastric triplication and peritoneal melanosis. The diagnostic criteria and the possible embryological origin are discussed.