The aim was to reassess the diagnostic value of turnout markers such as carcinoembryonic antigen (CEA), cancer antigen (CA) 15-3, CA 19-9 and CA 72-4 in the pleural fluid of various diseases, both in benign and malignant. Eighty-one patients (41 malignant and 40 benign pleural effusion) were included in this study. The effusion levels of CEA, CA 15-3, CA 19-9 and CA 72-4 were assayed with commercial enzyme immunoassays. CEA, CA 15-3, CA 19-9 and CA 72-4 mean pleural effusion fluid levels in malignant group were found to be significantly higher than that in benign group, but CA 19-9 mean pleural effusion fluid levels of malignant and benign group were similar. It was of interest to evaluate the prediction of the origin by pleural tumour markers. In pleurisies with a negative cytology, these assays are particularly useful when the clinical presentation cannot clearly exclude an underlying malignancy. (C) 2004 Blackwell Publishing Ltd.