The aim of this study Was to investigate the diagnostic value of interleukin 22 (IL-22) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 56 patients were classified on the basis of diagnosis as TPE (n=28) and M PE (n=28). The concentration of IL-22 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-22 in TPE was significantly higher compared to MPE (P<0.01). With a threshold value of 49 pg/ml, IL-22 had a sensitivity of 82.14% (23/28) and a specificity of 96.43% (27/28) for differential diagnosis. The combined detection of IL-22 and CEA had a sensitivity of 100% (28/28) and a specificity of 96.43% (27/28) to distinguish TPE from M PE. TPEs showed significantly higher levels of IL-22 compared to MPEs. The combined detection of IL-22 and CEA may be more valuable in the differential diagnosis between TPE and MPE.