A 44-year-old woman with atypical gyrate atrophy and iminoglycinuria was described. The serum ornithine level and ornithine-ketoacid transaminase (OKT) activity were both normal. Urinary excretion of proline, hydroxyproline and glycine was markedly increased. This finding, together with the existence of gyrate atrophy with hyperornithinemia due to OKT deficiency, suggests that proline deficiency in the chorioretinal tissues may concern the development of gyrate atrophy.