OBJECTIVE: To study the effect of astragalus on the proliferative ability of colony forming units granulocyte/monocyte (CFU GM) infected by human cytomegalovirus (HCMV) in vitro. METHODS: With the culture technique of CFU GM in vitro, the proliferation of CFU GM infected by HCMV was assayed in a group treated with astragalus and another one without astragalus. RESULTS: ①The numbers of CFU GM clusters and colonies in 2×10 5 cells in the astragalus treated group [( 333.33 ± 12.69 ) and ( 81.23 ± 4.93 ), respectively] were significantly greater than those in the un treated group [( 167.80 ± 16.63 ) and ( 53.70 ± 1.67 ), respectively](P< 0.01 ). ②The proportion of the production of big colonies in the astragalus treated group [( 9.5 ± 0.8 )%] was significantly higher than that in the un treated group [( 2.7 ± 1.0 )%] (P< 0.01 ). ③The peak time of big colonies appeared earlier, and the colony and big colony could last longer in the astagalus treated group compared with the un treated group. CONCLUSIONS: Astagalus may promote the proliferation of CFU GM infected by HCMV.