Body cavity lymphomas (BCLs) are a heterogeneous group of rare, primary non-Hodgkin's lymphomas that proliferate within the serous body cavities and result in recurrent effusions. This review is mainly focussed on the distinct entity primary effusion lymphoma (PEL) wherein the tumor clone is infected by human herpesvirus-8, the etiologic agent of Kaposi's sarcoma. In addition, we briefly discuss here recent data regarding other BCL types. The latter include a subset with no evidence of herpesvirus 8 which is associated with Epstein-Barr virus (pyothorax-associated lymphoma, PAL), the BCL forms associated to hepatitis C virus-related cirrhosis or alcohol-related cirrhosis and, finally, non-neoplastic forms mimicking lymphomatous effusions.