We conducted this randomized trial to investigate the efficacy and safety of rapamycin treatment in adults with chronic immune thrombocytopenia (ITP). Eighty-eight patients were separated into the control (cyclosporine A plus prednisone) and experimental (rapamycin plus prednisone) groups. The CD4⁺CD25⁺CD127(low) regulatory T (Treg) cells level, Foxp3 mRNA expression, and the relevant cytokines levels were measured before and after treatment. The overall response (OR) was similar in both groups (experimental group versus control group: 58% versus 62%, P = 0.70). However, sustained response (SR) was more pronounced in the experimental group than in the control group (68% versus 39%, P < 0.05). Both groups showed similar incidence of adverse events (7% versus 11%, P = 0.51). As expected, the low pretreatment baseline level of Treg cells was seen in all patients (P < 0.001); however, the experimental group experienced a significant rise in Treg cell level, and there was a strong correlation between the levels of Treg cells and TGF-beta after the treatment. In addition, the upregulation maintained a stable level during the follow-up phase. Thus, rapamycin plus low dose prednisone could provide a new promising option for therapy of ITP.