61 squamous cell cancers (27 laryngeal, 12 hypopharyngeal, 14 tonsillary, 8 tongue) with different keratinization and grading and seven lymph node metastases of HPV 16/18 positive carcinomas were analysed for the presence of HPV-DNA by in situ hybridisation. 65.5% of them were found to be positive. Twelve laryngeal carcinomas (44%), five tonsillary tumours (35.7%), eight tumours of the hypopharynx (66.6%) and three tongue carcinomas (37.5%) were shown to contain HPV 16/18 DNA. The detection rates of HPV 6/11 were lower. 44 of the analysed tumours (72.1%) had a grading G2. 29 of these tumours (65.9%) were HPV positive. Only eight of the patients were no heavy smokers or alcoholic drinkers. One of the lymph node metastases was positive for HPV 16/18. The results indicate that HPV may be involved in the pathogenesis of squamous cell carcinomas of head and neck tumours.