We report the case of a 13-year-old girl who presented mixed polyposis coli and gastric polyps. The rectal and colonic polyps were of the adenomatous and hamartomatous type (i. e. juvenile and Peutz-Jeghers polyps) without any intermediate features; in the stomach, the polyps were of the hyperplastic type. Microadenomas of the appendix and lymphoid hyperplasia of the ileum were also found. The karyotype was normal and the HLA group was A2 B12. No family history of polyps was discovered. To our knowledge no such case (complex polyposis) has been previously described. The present findings suggest that the usual pathological classification of polyposis may be arbitrary and that various pathological types may represent different aspects of the same spectrum of disease. Absence of "intermediate" polyps rule out the hypothesis of the sequence "hyperplastic polyp-juvenile polyp-adenoma".