Objective: To analyze the changes in peripheral natural killer T-cells (NKT) and gammadelta T-cells (γδT-cell) in patients with minimal residual leukemia (MRL) before and after being treated with Yiqi Bushen Granule (益气补肾颗粒, YBG) in order to determine their significance in prognosis of the disease. Methods: Before and after treatment, the changes in 36 patients (16 males and 20 females) receiving long-term (more than 3 months) YBG therapy were analyzed using multi-parameter flow cytometry, with 34 healthy persons (19 males and 15 females) acting as controls. Results: The absolute value and percentage of NKT cells and γδT-cells were all significantly raised after treatment, for NKT cells, 0.52%±0.39% to 0.83%±0.66% and 7.25±7.77 cell/μL to 12.86±11.99 cell/μL, for γδT-cells, 6.08%±3.03% to 7.24%±2.78% and 83.97±48.09 cell/μL to 110.53±54.12 cell/μL, respectively (P0.05 or P0.01). Conclusion: YBG could regulate the immune function and elevate the amount of NKT cells and γδT-cells, thus to kill or suppress the residual leukemic cell in the body, which might be one of the mechanisms of YBG in prolonging the disease-free survival in MRL patients.