Two retina specific cDNAs have been isolated by differential colony hybridization to retina and brain, and one of them, pCR-394, was identified as an opsin cDNA. By Northern hybridization experiment, the opsin cDNA hybridized to two species of bovine mRNA, one approximately 18 S (1800 bp) and the other 22 S (2600 bp). Using pCR-394 as a probe two opsin clones, R-5 (about 1200 bp) and LR-8 (about 2500 bp), were isolated from a cDNA library which was prepared by the method of Okayama-Berg. Each had a different length of 3'-untranslated DNA. The nucleotide sequences of R-5 and LR-8, as well as Northern and Southern hybridization experiments suggest that at least two species of opsin mRNA are expressed from a single gene. When the effects of illumination were examined by Northern hybridization and translation assays, the ratio of the two opsin mRNA species was changed between light- and dark-adapted eyes.