The case of 17-year-old boy with thalassemia major who contracted the human immunodeficiency virus (HIV) through multiple transfusions is described. Eight years after the onset of generalized lymphadenopathy, and 5 years after the documentation of HIV infection on serologic grounds, he developed the first of multiple, painful, subcutaneous nodules, which proved to be leiomyosarcomas of vascular origin. The histopathology and possible pathogenesis of these unusual tumors are discussed.