The caspases are known to play a pivotal role in the triggering and execution of apoptosis in virtually all cell types. Because inappropriate apoptosis is a prominent feature of many human diseases, the caspases are attractive targets for therapeutic intervention, In the present study we investigated whether Jurkat T lymphocytes rescued from Fas-induced cell death through the inhibition of caspases are functional. Here we show that the pan-caspase, tripeptide inhibitor, benzyloxycarbonyl-Val-Ala-Asp (Ome) fluoromethylketone (z-VAD-FMK), inhibited the activation of caspase-2, -3, -7, and -8, and subsequently apoptosis in Jurkat T lymphocytes induced by agonistic anti-Fas, The apoptotic signals induced by the cross-linking of the Fas antigen have a relatively long half-life, as z-VAD-FMK had to be continuously present in the culture medium for 72 h after Fas stimulation in order to maintain cell survival. After 72 h, the z-VAD-FMK-rescued cells proliferate normally and responded to activation induced cell, death after phytohaemaglutinin treatment, and readily undergo apoptosis when restimulated with agonistic Fas antibodies. Taken together, our results demonstrate that Jurkat T cells rescued from Fas-mediated cell death through the inhibition of caspases are functional,