 The purpose of the study is to investigate the role of paternal exposures in the etiology of sporadic heritable retinoblastoma RBL. The study has a matched case-control design with a sample size of 255 pairs. Cases will be children with sporadic heritable RBL identified from eight hospitals that together treat most of the RBL patients in the U.S. and Canada. We will use regional controls matched on year of birth and stateprovince of residence identified by randomdigit-dialing RDD. Fathers and mothers of cases and controls will be interviewed by telephone about their occupational, medical, dietary, and personal exposures before the index childs conception. Blood samples will be obtained on cases and their parents for DNA isolation. The cases DNA will be used to characterize the disease-causing RB1 mutation. The parents DNA will be used to detect the few instances in which a parent also has the RB1 mutation, i.e., the childs RBL is familial rather than sporadic. 