Organic acids have been determined in aqueous humour and plasma by gas chromatography-mass spectrometry in 38 cases of infant death and 4 cases of inherited metabolic disease: one had a complex fatty-acid oxidation disorder with a large urinary excretion of adipic acid, the others had a disorder of propionate catabolism with a large urinary excretion of methylmalonic acid. In each case we found in aqueous humour the abnormal metabolite present in urine. Thus aqueous humour could be a suitable material for retrospective diagnosis of inherited metabolic diseases at autopsy in sudden infant death syndrome.