Predictive testing using molecular analysis is an integral part of contemporary retinoblastoma management. We have made extensive use of segregation analysis for risk assessment in both familial and sporadic disease. Investigation of loss of heterozygosity in tumor samples proved to be invaluable for the identification of linkage phase. In many families, however, accurate carrier risk assessment depends on direct identification of the causative R B I mutation. Consequently, we have developed methods for rapid mutation screening. Using these techniques, mutation analysis can now be offered to an increasing number of individuals.