分析４０ 例结核性胸膜炎，１４ 例癌性胸膜炎和８ 例细菌性胸膜炎患者血清和胸水腺苷脱氨酶（ Ａ Ｄ Ａ） 活性。结果显示：结核性胸水 Ａ Ｄ Ａ 活性显著高于细菌性和癌性胸水（ Ｐ＜ ０ ．０１） ；结核性胸水患者 Ａ Ｄ Ａ 胸水／ 血清比值＞ １ ，而细菌性、癌性胸水患者则＜ １ ，两者比较差异有显著性（ Ｐ＜ ０ ．０１） 。提示这二项指标有助于结核性胸膜炎和细菌性、癌性胸膜炎的鉴别诊断。 Serum and pleural fluid adenosine deaminase (ADA) activity was analyzed in 40 patients with tuberculous pleurisy, 14 patients with cancerous pleurisy and 8 patients with bacterial pleuritis. The results showed that A D A activity of tuberculous pleural effusion was significantly higher than that of bacterial and cancerous pleural effusion (P <0.01); tuberculosis pleural effusion A D A pleural effusion / serum ratio> 1, while bacterial and cancerous pleural effusion <1, the difference between the two was significant (P <0 .01). Prompt these two indicators contribute to the differential diagnosis of tuberculous pleurisy and bacterial, cancerous pleurisy.