Between 1987 and 1992, 39 radioimmunoscintigraphic studies using In-111-labelled antimyosin Fab fragments were performed in 27 patients with rhabdomyosarcoma (RMS), 2 patients with leiomyosarcoma (LMS) and 1 with alveolar soft tissue sarcoma. 21 patients were children aged 3-14 years. These patients, who had histologically proven myosarcoma, were examined scintigraphically to search for local recurrences or metastases and to determine the response to treatment. The results of immunoscintigraphy were compared with histopathological parameters and other imaging modalities. The sensitivity of antimyosin scintigraphy in this series was 82% and the specificity was 73%. Although the technique appears to be not highly specific for RMS, it was found to be useful for the early detection of local recurrence and metastases, as well as for the evaluation of the response to therapy.