It has been suggested that alterations of cell cycle genes probably contribute to the pathogenesis of endemic Burkitt's lymphoma (BL) in addition to c-MYCtranslocation. Mutations disrupting the normal nuclear localization signal of the retinoblastoma-related geneRb2/p130have been documented in BL cell lines and primary tumors from endemic areas. The aim of this study was to investigate the involvement ofRb2/p130gene in the pathogenesis of sporadic BL in Brazil. DNA samples from 26 pediatric BL tumors and two healthy blood donors were screened by PCR amplification followed by single strand conformation polymorphism analysis of exons 19 and 20 (B domain) and exons 21 and 22 (C-terminus), where most of the point mutations in theRb2/p130gene were identified. No abnormal band shifts were present in the samples analyzed. We concluded that mutations in exons 19-22 of theRb2/p130are unlikely to be involved directly in the pathogenesis of sporadic Brazilian BL.