The autism spectrum disorders (ASDs) are complex diseases with a strong genetic component. Numerous candidate gene studies have tested association between various functional and positional candidate genes and autism, but no common variation predisposing for autism has been identified to date. It has been previously proposed, that glyoxalase 1 (GLO1) might be involved in the pathogenesis of autism as GLO1 protein polarity was significantly changed in the brains of autism patients compared to controls. GLO1 harbors a functional polymorphism that affects the polarity and the enzymatic activity of the protein. In the same study, this polymorphism showed a suggestive association to autism. To investigate whether common variants in GLO1 predispose to autism in the Finnish population, we have genotyped six polymorphisms in GLO1 in families with more than 230 individuals affected with ASDs and carried out both linkage and association analyses. We did not observe significant linkage or association between any SNP and ASDs. Therefore, we suggest that common variants in GLO1 are not significant susceptibility factors for ASDs in the Finnish population. © 2007 Wiley-Liss, Inc.