The objective of this retrospective study was to investigate the prevalence of retinal diseases in dogs presented to the Veterinary Medical Teaching Hospital, Seoul National University from April 2004 to December 2005. Sixty-five dogs (120 eyes) with retinal diseases involving blindness were included in this study. Age, breed, and gender data for all breeds were collected from medical records documenting vision loss. Generalized progressive retinal atrophy (gPRA) was the most common manifestation. Other prevalent findings included sudden acquired retinal degeneration (SARD) and retinal detachment (RD). Bilateral gPRA was found in 32 dogs with a female-to-male ratio of 1 : 1. The mean $age{pm}SD$ of all dogs in this group was $4.66{pm}2.30$ years with a range of 3 to 12 years. Breeds with highest prevalence of gPRA were Miniature Schnauzer (24/32, $mean{pm}SD$ age: $3.79{pm}0.78$ yr) and Poodle (2/32, $6.50{pm}0.71$ yr). Twelve dogs (24 eyes) were diagnosed with SARD bilateraly, ranging from 3 to 13 years of age ($mean{pm}SD:;6.91{pm}2.61$ yr). There were no abnormalities in fundus of 11 dogs at presentation. Electroretinography (ERG) without anesthesia was performed in 7 dogs, and all response was totally extinguished. Retinal detachment was identified in 21 dogs (32 eyes): 11 bilateral and 10 unilateral (7 right eye, 3 left eye). The most common breed was Shih Tzu (15/21, $mean{pm}SD$ age: $4.39{pm}3.24$ yr). Four other breeds comprised the remaining 6 cases (8 eyes). The everall mean age of the group was: $4.18{pm}2.89$ years (range 0.8 to 14 years) with a female-to-male ratio of 1 : 1.1 (10 females, and 11 males).