Hyperglycaemia induces neural tube defects and growth retardation in cultured mouse and rat embryos. In this study the possibility that glycine could prevent hyperglycaemia-induced embryopathy was researched. Early somite mouse embryos were cultured in normal medium, hyperglycaemic medium (50 mmol L(-1) glucose), or with glycine (1 mmol L(-1)) supplementation of normal and hyperglycaemic rat serum for 48 h. The embryo growth and differentiation were determined to estimate developmental and congenital malformations as well as lipid peroxidation levels. Adding glycine to the control culture medium did not affect embryonic development. Whereas the amino acid protected against telencephalon dysmorphogenesis, the decreased DNA content and number of somites, and the morphological score affectation induced by the hyperglycaemic medium, it had no preventive effect on the retarded differentiation of the otic system. Moreover, it prevented the high hyperglycaemia-induced lipoperoxidation levels of embryonic tissues. Embryos were partially protected from the hyperglycaemia-induced teratogenesis due to the antioxidative effect of glycine. As no other mechanisms related to the antiglycation or other protective effects of glycine were examined, the mechanism whereby it acted as an antiteratogenic agent needs further study.