The aim of this study was to evaluate the individual and combined diagnostic value of five tumour markers in the elderly patients with pleural effusions. Serum and pleural fluid levels of cytokeratin fragment 19 (CYFRA21-1), neuron-specific enolase (NSE), carbohydrate antigen 15-3 (CA15-3), carbohydrate antigen 19-9 (CA19-9) and carbohydrate antigen 125 (CA125) were assayed in 32 elderly patients with malignant pleural effusions resulting from advanced lung cancer and in 30 elderly patients with benign pleural effusions by ELISA. Serum levels of CYFRA21-1, NSE, CA15-3, CA19-9 and CA125 in patients with malignant pleural effusions were 12.84 +/- 6.48 microg/l, 22.07 +/- 11.25 microg/l, 65.74 +/- 30.26 kU/l, 56.32 +/- 25.6 kU/l and 71.86 +/- 31.45 kU/l, respectively, and were significantly higher than those in patients with benign pleural effusions (p < 0.01). Pleural fluid levels of CYFRA21-1, CA15-3, CA19-9 and CA125 except NSE in patients with malignant pleural effusions were 18.64 +/- 8.15 microg/l, 59.31 +/- 27.35 kU/l, 48.24 +/- 21.56 kU/l and 62.16 +/- 27.79 kU/l, respectively, and were significantly higher than those in patients with benign pleural effusions (p < 0.01). The parallel combined testing of five tumour markers in serum increased the diagnostic sensitivity to 90.6%, and serial combined testing increased the diagnostic specificity to 93.3%. The sensitivity (%) and specificity (%) of these tumour markers in pleural fluid were as follows: CYFRA21-1, 84.4/90; CA15-3, 62.5/73.3; CA19-9, 37.5/66.7; CA125, 56.3/70; for differentiating malignant effusions from benign effusions. When CYFRA21-1 and CA15-3 combined, the sensitivity and specificity were increased (100% and 90% respectively). Serum and pleural fluid levels of the five tumour markers shows certain values in the diagnosis and differentiate diagnosis for malignant pleural effusions in the elderly patients from benign. The combined assay of five tumour markers in serum and the CYFRA21-1 combined with CA15-3 in pleural fluid were helpful and can increase the sensitivity and specificity in diagnosing malignant pleural effusions.