A cytogenetic study of two cases of alveolar soft part sarcoma showed near-diploid karyotypes with multiple chromosomal rearrangements. An abnormality of the long arm of chromosome 17, involving band q25, is present in both cases and in 2 of 4 cases in the literature. This recurrent structural abnormality probably plays an important role in the histogenesis of this unusual neoplasm and therefore is important for further molecular investigation.