The Epstein-Barr virus (EBV) is directly implicated in the pathogenesis of a variety of undifferentiated carcinomas and has also been identified in conventional adenocarcinomas of the stomach. To date, the association of EBV with non-small cell lung carcinoma is restricted to Asian patients. To evaluate the presence of EBV in lung cancers from Europeans, we investigated primary lung adenocarcinomas with a similar morphological tumour pattern to those of the stomach, specifically rare tumours with components of signet-ring cells. Three tumours of signet-ring cell type were examined by means of polymerase chain reaction (PCR). To localise the virus to the neoplastic cells, in situ hybridisation (ISH) was performed using an antisense Epstein-Barr virus encoded RNA probe. Immunohistochemistry was performed to evaluate the expression of latent membrane protein-1 (LMP-1) and EBV nuclear antigen 2 (EBNA-2). PCR investigation confirmed the presence of EBV in one case. Positive signals confined to tumour cells were present on ISH. None of the tumours showed expression of LMP-1 and EBNA-2. To our knowledge, this is the first report on the presence of EBV in primary adenocarcinoma of the lung in a Caucasian patient. The present study indicates that EBV may infect some lung cancers with a specific tumour pattern.