Purpose: The aim of the study was to present the updated Institut Gustave Roussy experience of the predictive value of three biological parameters in patients with squamous cell carcinoma of the Head and Neck (HNSCC) treated with radiation therapy.Methods and Materials: Three parameters have been investigated independently: tumor cell kinetics (TS, T-pot and LI), oxygen tension measurements (PO2) and intrinsic radiosensitivity (SF(2)Gy).Results: No relationship has been found between local-regional control and T-pot or LI in a series of 74 patients, Our data also support that the surviving fraction at 2 Gy, (SF2) was unlikely to predict the clinical outcome in a series of 92 patients. Differences in PO2 measurements have been observed between tumors, and tumor oxygenation was lower than that of normal tissue for the majority of patient, However PO2 measurements did not predict clinical outcome, but further investigations are needed to draw definitive conclusions, given the limited number of patients entered in our study (35 patients), In addition, we were able to measure the three parameters in 10 patients showing no correlation between PO2, SF2 and T-pot.Conclusions: The method used to evaluate T-pot and SF2 did not provide clinically relevant predictive parameters for this type of cancer, Further investigations are needed to assess the predictive value of PO2 measurements and of new biological parameters in a multiparametric approach, taking into account other possible clinical and biological confounding factors. (C) 1997 Elsevier Science Inc.