Objective: To assess the efficacy and safety of Zhongyan-4 (中研-4号, ZY-4, a Chinese herbal preparation worked out according to the therapeutic principle of supplementing qi, nourishing Yin,clearing heat and detoxication) in treating HIV/AIDS patients in the early or middle stage. Methods: Adopted was randomized double-blinded and placebo-parallel-controlled method, with 72 HIV/AIDS patients randomly divided into the ZY-4 group (36 patients) treated with ZY-4 and the control group (36 patients) treated with placebo. The treatment course was six months. The index of CD4+ , CD8+ counts, body weight, clinical symptom scoring were estimated at 4 time points (0, 1, 3 and 6 month in the course), and also the viral load before and after treatment. The whole course of observation was completed in 63 patients, 30 in the ZY-4group and 33 in the control group. Results: CD4 + count in the ZY-4 group got elevated by 7.70 ± 150.96/mm3on average, while that in the control group lowered by 27.33±85.28 /mm3. Fifteen out of the 30 patients in the ZY-4 group had their CD4+ count increased, which was evidently much higher than that in the control group (8/33, P＜0.05), suggesting that the efficacy of ZY-4 is superior to that of placebo in elevating CD4 +count. Moreover, ZY-4 showed actions in elevating CD45RA+ and CD8+ count, reducing HIV virus load, improving clinical symptom/sign and increasing body weight of patients. No obvious adverse reaction was found in the clinical trial. Conclusion: ZY-4 has an immunity-protective and/or rebuilding function in HIV/AIDS patients in the early and middle stage, and also shows effects in lowering viral load, increasing body weight and improving symptoms and signs to a certain degree.