Juvenile (embryonal and alveolar) rhabdomyosarcoma of the head and neck in adults. A clinical, pathologic, and immunohistochemical study of 12 cases. Sites in the head and neck region (orbit, nasopharynx, nasal cavity, etc.) are among the most frequent locations for juvenile (embryonal and alveolar) rhabdomyosarcomas in patients younger than 15 years; however, comparable neoplasms in adults are very uncommon. A clinicopathologic and immunohistochemical study of 12 juvenile rhabdomyosarcomas in patients between the ages of 18 and 36 years is presented. There was a female:male ratio of 2:1. The orbit with or without contiguous paranasal sinus involvement, nasal cavity, sphenoid sinus, middle ear, and soft tissues of the neck and preauricular region were the primary sites. Seven tumors involved a parameningeal site and eight cases were alveolar rhabdomyosarcomas which together contributed to the adverse outcome. Only two patients were long-term, disease-free survivors. Six patients have died of tumor and two others are alive with persistent disease. Immunohistochemical study in 11 cases demonstrated reactivity for vimentin and muscle-specific actin (HHF-35) and desmin in ten cases. Juvenile rhabdomyosarcoma rarely presents in the head and neck of adults but should be considered in the differential diagnosis of a small cell neoplasm in patients during the third and fourth decades of life. 