To investigate the diagnostic value of adenosine deaminase (ADA) in immunocompromised hosts with tuberculous pleural effusions, we collected and checked 60 pleural effusion specimens from admitted patients. These patients were divided into three groups: group I (n = 20), immunocompetent hosts with tuberculous pleural effusions; group II (n = 10), immunocompromised hosts with tuberculous pleural effusions; and group III (n = 30), patients with malignant pleural effusions. Using statistical analysis to compare the ADA value in each group, the p value was found to be significant between groups I and II (p < 0.01), groups I and III (p < 0.001) and groups I+II and III (p < 0.001); however, the p value was not significant between groups II and III. If the lowest ADA value for the tuberculous pleural effusion was designed as 80 U/L, the sensitivity/specificity was 1.0/0.90 (group I), 0.40/0.90 (group II), and 0.80/0.90 (group I+II), respectively. We conclude that the diagnostic value of ADA in immunocompromised hosts with tuberculous pleural effusions is not as significant as in immunocompetent hosts.