The Bleomycin (BLM)-induced apoptosis in peripheral blood mononuclear cells (PBMC), from patients with advanced squamous cell carcinoma of the head and neck (SCCHN), cultured in vitro with PHA, was tested as a predictive indicator of the survival time. The rates of the PBMC BLM-induced apoptosis and of the cycling-PBMCs, measured respectively after Giemsa- and Feulgen-staining were determined in 25 patients before induction chemotherapy. By using the Cox model, the survival probability was significantly and independently increased for a high percentage of PBMC BLM-induced apoptosis and a high rate of cycling PBMCs. (Chi-2(2): 10; p=0.007). Six patients, in whom both PBMC variables were simultaneouly greater than the median values, showed a median survival time as long as 60 months versus 10 months for the other 19. Conclusively, the PBMC susceptibility to BLM-induced apoptosis as well as the PBMC capability for cycling may be regarded as independent pretherapeutic prognosis factors for patients with advanced SCCHN.