The authors report a case of a collision tumor composed of a primary gastric rhabdomyosarcoma intermingled with an adjacent infiltrating gastric adenocarcinoma. Only eight cases of gastric rhabdomyosarcoma have been reported previously and little information is recorded about the behavior of this tumor. Gastric rhabdomyosarcoma has several distinctive clinical features. It is a highly aggressive tumor (median survival, 2.5 months) occurring in both children and adults and frequently presents as metastatic disease to lung or cervical lymph node. The initial diagnosis is often difficult to establish, especially on biopsy material. In several instances, the correct diagnosis was established only at autopsy. The authors' patient was correctly diagnosed during life and received considerable benefit from cyclophosphamide, doxorubicin, and vincristine (CAV) therapy and survived for 26 months after diagnosis. Two of the previously reported eight cases of primary gastric rhabdomyosarcoma and this case have adjacent admixed glandular gastric adenocarcinomas. Since three of the nine known cases of primary gastric rhabdomyosarcoma have an adjacent admixed gastric adenocarcinoma, there appears to be a greater than chance association between these two tumors.