We report a rare case of leiomyosarcoma in the bladder which occurred in an 18-year-old female with a prior history of retinoblastoma (RB). Molecular characterization of this tumor displayed a homozygous RB deletion and a reduced p53 expression. These results suggest that the loss of RB and p53 may have contributed to the initiation and/or progression of the leiomyosarcoma of the bladder in this patient. Copyright (C) 2003 S. Karger AG, Basel.