The authors report a family in which a Thr58Arg rhodopsin mutation co-segregates with the disease phenotype of autosomal dominant retinitis pigmentosa (RP) in 16 family members. DNA sequence determination confirms the presence of the same mutation reported previously for one family apparently unrelated to the pedigree now reported. Features of RP in this family included a later onset of symptoms, with night blindness first noticed between ages 12 to 24 years. Although symptoms worsened with age, no complete blindness was observed even with advanced age. Results of psychophysical and electrophysiologic testing showed that a 19-year-old affected woman and her 65-year-old affected uncle had relatively similar extent of visual dysfunction, and that the vision of both was better than 2 of their relatives aged 37 and 53 years. This study presents a range of phenotypic similarities and differences observed between individuals whose RP appears to be caused by the same mutation.