Alcohol consumption by mothers during pregnancy causes a fetal alcohol syndrome associated with massive neuronal apoptosis. We have recently shown that taurine at a dose of 2 g/kg saves about 50% of dying cerebellar neurons from ethanol-induced apoptosis in 7-day-old mice. However, a further increase in the taurine dose to ethanol-treated mice had a toxic and in some cases lethal effect. In the present work we studied the toxic effects of taurine and ethanol coadministration in three age groups: 7-day-old, adult (5 to 6 months old), and old (12 to 13 months old) mice. Taurine and ethanol were injected in two half-doses: taurine at 0 and 4 h and ethanol at 1 and 3 h. The minimal 100% lethal doses in coadministration of taurine and ethanol were the following: 7-day-old mice-6 g/kg taurine + 5 g/kg ethanol, adult mice-10 g/kg of taurine + 8 g/kg of ethanol, and old mice-above 6 g/kg of taurine + 6 g/kg of ethanol. All mice treated with taurine or ethanol alone survived. The adult and old mice dying from the combined toxicity of taurine and ethanol showed a marked fall in blood glucose, which may be one reason for lethality. A comparison of the lethal doses of taurine and ethanol coadministration in different age groups allows us to conclude that the adverse effect of the combined toxicity of taurine and ethanol is age dependent.