We have analysed organic acid profiles in 74 samples of post-mortem vitreous humour from the sudden infant death syndrome and compared the profiles to those obtained from the corresponding urine or bladder wall swab. There was a high degree of correlation indicating that vitreous humour analysis in high-risk infants is an appropriate analytical strategy when urine is not available. In our patient sample two infants had evidence of abnormal methylmalonic acid metabolism, one had glyceric aciduria (and elevated levels of vitreous humour glyceric acid), one had evidence of pre-existing liver damage as judged by the presence of 4-hydroxyphenyllactic acid, one had a non-ketotic dicarboxylic aciduria indicating inhibited fatty acid oxidation and two patients had significant long-chain 3-hydroxydicarboxylic acids and evidence of paracetamol ingestion.