Behr's syndrome consists of recessively inherited infantile optic atrophy, together with chronic neurological disturbances such as ataxia, extrapyramidal dysfunction, and juvenile spastic paresis. This syndrome was found to be relatively common among Iraqi Jews. For our study, 18 such patients underwent metabolic study. All 18 showed abnormally elevated excretion of 3-methylglutaconic acid in their urine. The basic enzymatic defect is as yet unknown. We recommend that patients with early optic atrophy, and especially those with motor dysfunction, be examined for this organic aciduria.