多药耐药（multidrugresistanceMDR）是导致化疗失败或复发的主要障碍，体外研究证实环孢菌素A（CsA）对使MDR细胞内药物浓度恢复至敏感水平。在体内能达到逆转耐药所需的CsA浓度，赵春亭等[1]用CsA逆转1例M4b白血病的MDR取得了完全缓解。我们应用CsA、rhG－CSF联合化疗治疗6例 Multidrug resistance (MDR) is a major obstacle to chemotherapy failure or relapse, and in vitro studies have demonstrated that cyclosporin A (CsA) restores drug levels in MDR cells to sensitive levels. Reversal of CsA concentrations required to reverse drug resistance can be achieved in vivo. Zhao Chunting et al. [1] achieved complete remission of MDR in M4b leukemia with CsA. We used CsA, rhG-CSF combined with chemotherapy in 6 cases