Embryonal rhabdomyosarcomas consist of two histological variants; it can be distinguished between solid embryonal rhabdomyosarcomas and botryoid sarcomas. We investigated 13 solid and 7 botryoid rhabdomyosarcomas and used 46 biopsies of 20 patients between 6 weeks and 14 years old. There were 12 male and 8 female patients. The histologic examination yielded variations of cytologic pattern and tissue structure. Besides undifferentiated sarcoma cells which constituted the majority of tumor cells and a changing amount of rhabdomyoblastic cells (but only 40% of all tumors showed cells with cytoplasmic cross striation) in 6 solid and 6 botryoid tumors some other cellular features could be observed. There were tumor cells with characteristics of lipoblasts and histiocytes, and occasionally the potency to form vascular spaces was detected, too. The histochemical examination proved the presence of glycosaminoglycans and mucoproteins. The glycosaminoglycans seemed to contain only a few sulphated groups. In agreement with a preceding electron microscopic study of botryoid sarcomas in the nasopharynx (Katenkamp et al. 1979) we stated that many so-called embryonal rhabdomyosarcomas show the basic pattern of an undifferentiated embryonal sarcoma and have some diverging cellular differentiations. Therefore, it is an open question whether the term "embryonal rhabdomyosarcoma" should be defined more precisely than usually done in the routine histological work today.