P53 and CCND1 (cyclin D1) genes play a critical role in the cell cycle regulation. Abnormalities of these genes are frequent in different types of cancers, including those of the head and neck. The aim of this work is to investigate whether P53 inactivation (determined by loss of heterozygosity analysis) is related to CCND1 gene amplification (determined by differential PCR analysis), and if these alterations are correlated with clinical outcome in a series of 56 patients with squamous cell carcinoma of the head and neck. Loss of heterozygosity of the P53 gene was found in 39 cases (70%) and CCND1 amplification in 17 cases (30%). Both abnormalities together were found in 11 cases (20%), without a significant association between them (P = 0.83). No relationship was found between P53 inactivation, the clinico-pathological parameters analyzed and the clinical outcome. CCND1 amplification was associated with advanced T-stages (P = 0.02), nodal metastases (P = 0.01) and a decreased survival (P = 0.002). The combination of both abnormalities shows a pattern that seems to be additive, since it was associated with an increase in tumor recurrences and a decrease in survival that was higher than for either of them individually. In conclusion, P53 and CCND1 abnormalities are frequent in squamous cell carcinomas of the head and neck. The combined analysis of these abnormalities seems to be more informative than either of them individually and may have a prognostic value in these carcinomas.