Human papillomavirus integration in cellular DNA and loss of heterozygosity of P53 gene are both related with tumour formation process by promoting genomic instability that leads to DNA abnormalities accumulation. In order to analyze the relationship between both events, 26 squamous cell carcinomas of the head and neck were studied. HPV 16 and 6b DNA was detected by PCR in 8 cases (31%), whereas P53 loss of heterozygosity was present in 16 cases (61%). No correlation was found between both events and they were not related to clinical factors neither the prognosis. Consequently, HPV integration and loss of heterozygosity of P53 seem to act independently in the genesis of these tumours.