A 10 year old white girl is presented with gyrate atrophy of the choroid and retina (atrofia gyrata). She also showed reticular pigmentations at the level of the retinal pigment epithelium temporal to both maculas. A generalized hyperornithinaemia was demonstrated in this patient and cultured fibroblasts established the underlying ornithine-keto-acid-transaminase (OKT) deficiency for the first time. Pharmacologic doses of vitamin B6 nor restriction of dietary protein resulted in a significant decrease of the serum ornithine concentration. It is probable that hyperornithinaemia in itself is not the cause of the gyrate atrophy.