Teratogenic tumors are characteristic for childhood. For a period of 15 years the authors have observed 12 children with retroperitoneal and pelvic-presacral localization of teratogenic tumors. They were most common in girls under one year of age. The clinical symptoms, the methods applied for diagnosis are analysed; the diagnostic importance of rectal digital examination, inferior venacavography and especially of computer tomography is emphasized. Radical removal of the tumor was performed in 11 children and biopsy in 1. The most convenient operative access to pelvic-presacral-retroperitoneal tumors is a one-step double access (abdomino-sacrococcygeal). As a result of complex treatment--surgical and chemotherapy--the postoperative results were good in 9 children.