Objective To investigate the clinical efficacy of Zaizao Shengxue ( Blood-engendering Renewal) Capsule (ZZSXC) in the treatment of myelodysplastic syndrome. Methods A total of 139 patients who met the diagnostic criteria of Chinese and Western medicine for myelodysplastic syndrome were enrolled according to the principles of randomized multicenter controlled trials. The 103 patients in the treatment group were given 5 ZZSXCs each time, thrice daily. The 36 patients in the control group were given 8 Fufang Zaofan (Compound Zaofan) Pills (FFZFP) each time, thrice daily. The two groups were treated for 3 months. Then their hematological improvements in HI-E, HI-P and HI-N and peripheral blood parameters (HGB, RBC, MCV, PLT, WBC and NEUT) as well as subgroup analysis, TCM pattern and physical sign scores, bleeding, infection, clinical efficacy and safety were evaluated. Results In both the treatment group and the control group, the overall percentages of improvement in such hematological parameters as HI-EE, HI-P and HI-N were 51. 6% and 38. 5%, 44. 8% and 40. 0%, and 51. 0% and 68. 2% respectively without statistically significant difference between the two groups (P >0.05). The diferences in RBC and HGB of all the patients and the subgroup of low-risk patients in the treatment group before and after treatment were statistically significant (P <0. 05) . The diferences in WBC of the subgroup of high-risk patients in the treatment group before and after treatment were statistically significant (P <0. 05) . The diferences in NEUT of all the patients and the subgroup of low-risk patients in the control group before and after treatment were statistically significant (P <0. 05). MCV was decreased of the subgroup of low-risk patients in the treatment group after treatment compared with that before treatment with statistical significance ( P < 0. 05 ) . The percentages of patients that enjoyed marked curative effects and curative effects in terms of TCM patterns in the treatment group and the control group were 29. 9% and 30. 3%, and 62. 1% and 57. 6%, respectively, with no statistically significant diference between the two groups ( P > 0. 05 ) . There was no statistically significant diference in curative effects for individual symptoms and signs between the two groups (P >0. 05) . There was no statistically significant dUference in hemostasis, incidence of infection and safety parameters between the two groups (P > 0. 05 ) . Conclusion Both ZZSXC and FFZFP can improve morbid hematopoiesis and hematological parameters in patients with MDS, and remarkably improve their TCM patterns and individual symptoms and signs with good clinical drug safety. [ABSTRACT FROM AUTHOR]