We report on an alveolar rhabdomyosarcoma occurring in a 17-year-old girl. Histologically, the tumour exhibited a proliferation of small, round cells and formed alveolar structures. Immunohistochemical studies of the tumour cells showed desmin and creatine kinase MM positivity. In electron-microscopic studies, the tumour cells showed an abundance of glycogen granules, and myofilaments were recognized in the cytoplasm. Chromosome analysis revealed a translocation, t(2;13)(q37;q14), which is though to be common in this subtype of rhabdomyosarcoma. Conventional ultrastructural and immunohistochemical investigations and chromosome analysis thus appear to be a highly promising combination of methods for improved pathological diagnosis of alveolar rhabdomyosarcoma.