To establish syntenic relationships of phototransduction genes, we have mapped the genes encoding the α-, β-, and γ-subunits of rod cGMP phosphodiesterase (PDE) (PDEA, PDEB, PDEG), the α'-subunit of cone PDE (PDEA2), and the rod cGMP-gated channel (CNCG) to bovine syntenic groups. The rod cGMP PDE α-, β-, and γ-subunit genes map to bovine syntenic groups U22, U15 (chromosome 6), and U21 (chromosome 19), respectively. The rod cGMP-gated channel gene also maps to syntenic group U15, and the bovine cone α'-subunit gene maps to U26 (chromosome 26). With the exception of the cone PDE α'-subunit gene, which has not been mapped in other mammals, all of these genes have been assigned to conserved chromosomal regions shared among bovine, human, and mouse. A compilation of currently known syntenic assignments and predictions regarding future assignments of phototransduction genes in human, mouse, and cattle is presented. © 1992 Academic Press, Inc. All rights reserved.