Azide is reported to be an inducer of necrotic rather than apoptotic cell death. Using various parameters of cell death, we demonstrate here that azide is capable of completely inhibiting apoptosis induced by VP-16/etoposide. Azide was found systematically to protect Jurkat cells against VP-16-induced effects as determined by an array of biochemical and morphological parameters. The cells were able partially to recover proliferative activity following removal of the drugs. We conclude that azide inhibits apoptosis induced by VP-16 at an early point in the apoptotic pathway and that inhibition of apoptosis might be the mechanism of necrosis-induction by azide.