Recently several methods have been described for triggering extensive apoptotic neurodegeneration in the developing in vivo mammalian brain. These methods include treatment with drugs that block NMDA glutamate receptors drugs that promote GABAA neurotransmission or treatment with ethanol which has both NMDA antagonist and GABAmimetic properties. A single intoxication episode induced by any of these agents is sufficient to cause widespread neurodegeneration throughout many brain regions. The cell death process transpires rapidly from early to late stages within several hours. As the neurons die they become TUNEL positive and show by both light and electron microscopy all of the classical morphological characteristics of apoptosis. In the present study using immunocytochemical methods we document that ethanol intoxication of 7-day-old infant mice causes a widespread pattern of caspase-3 activation corresponding to the pattern of apoptotic neurodegeneration that is occurring simultaneously.