Here we present evidence implicating disrupted RNA splicing as a potential cause of inherited tritan color vision. Initially we tested 51 subjects for color vision deficiencies. One made significant tritan errors; the others were classified as normal trichromats. The putative tritan subject was the only one of the 51 subjects found to be heterozygous for an OPN1SW gene mutation that disrupts RNA splicing in an in vitro assay. In order to gather further support for the role of the splicing mutation in tritan color vision, the putative tritan subject's mother and sister were examined. They also made tritan errors and had the same OPN1SW gene mutation.