The aim of this study was to evaluate the possible association of human papillomaviruses (HPV) with the development of squamous cell lung carcinomas (SqCLCs). Tissue material from 52 cases of SqCLCs were studied, and the data were evaluated according to the degree of differentiation, HPV presence and type. Analysis was performed by polymerase chain reaction (PCR) method using consensus primers, and the results were confirmed by subsequent Southern blot hybridization. Overall, the results showed 69% positivity (n=32). Forty-one cases were examined for the presence of specific HPV types (6/11 and 16/18) by hybridization of the PCR products with 32P-labelled probes. HPV 6/11 types were detected in 6 of the 29 positive cases (20.6%). HPV 16/18 types were the most prevalent types, and were detected in 11/29 cases (37.9%: 4/10 of well-differentiated cases, 6/25 of moderately and 1/6 of poorly differentiated carcinomas). Our results confirm the possibility that HPV might play a role in the development of SqCLCs and suggest a possible relation of high-risk HPV16/18 types to tumour differentiation.