The first symposium of the Society for the Study ofInborn valuable overview of advances in the application of Errors of Metabolism (SSIEM) on the organic acid urias chemical analysis of amniotic fluid to their early prenatal was held in Leeds in 1971 and published by the Society in diagnosis. The continuing complexity of diagnosis, 1972 (the 9th Annual SSIEM Symposium). Although biochemistry and aetiology ofthe dicarboxylic acid urias relatively few of these disorders were recognized at that has been admirably reduced by the papers from Dr time, the symposium was prompted by the then recent Gregersen and Dr Goodman, with Dr Goodman clearly identification between 1966 and 1970 of isovaleric identifying the primary defect in the polycystic variant of acidaemia, methylmalonic aciduria, propionic aci- multiple acyl CoA dehydrogenase deficiency ("glutaric daemia, pyroglutamic aciduria and 3-methylcrotonyl- aciduria type II") as a deficiency of electron transfer glycinuria. Identification and diagnosis of diseases of this flavoprotein (ETF) dehydrogenase. Dr Engel's paper kind had greatly improved primarily through the also provides a useful overview from currently available application of gas chromatography and mass spectro- data of the place of L-carnitine in the organic acid urias, metry to medicine, although the complexity of the an area in which rapid developments are occurring. The underlying biochemistry and the genetic heterogeneity of emerging understanding of the aetiologies of the the organic acidurias was not then realised.