We report on a boy with Rieger syndrome, who had an apparently balanced reciprocal translocation between chromosomes 1 and 4. The clinical manifestations of this patient were characterized by irregular shaped pupils with a prominent Schwalbe line and an umbilical hernia. On cytogenetic studies, he was found to have a de novo reciprocal translocation 46,XY,t(1;4) (q23.1;q25), without visible deletion. His parents had normal chromosomes. A review of both cytogenetic and genetic linkage analyses with Rieger syndrome showed that chromosome 4q was involved. This and other previous reports suggested that the gene for Rieger syndrome is mapped to the 4q25-->4q26 segment adjoining the breakpoint.