APOPTOSIS is a programmed cell death that occurs during the development of the nervous system and in neurodegenerative disorders. Tau protein is a microtubule-associated protein which promotes microtubule polymerization and stabilization. Apoptosis was induced in primary neuronal cultures by glutamate exposure (200 μM, 15 min) or by serum deprivation, and tau mRNA levels were studied by quantitative in situ hybridization in apoptotic and non apoptotic neurons. Compared to controls, tau mRNA expression was decreased in apoptotic neurons produced by excitotoxicity or trophic support withdrawal. Under these conditions, resistant neurons to apoptosis display either increased tau mRNA levels after glutamate exposure or a stable tau mRNA expression after serum deprivation. In conclusion, in thisin vitromodel, neurons which are resistant and sensitive to apoptosis can be differentiated according to tau mRNA expression.