OBJECTIVE：To c ompare the effects o f intravenous anesthesia with remimazolam and propofol on perioperative cellular immune function in patients underwent radical mastectomy. METHODS ：Eighty patients underwent selective radical mastectomy were collected ，and then randomly divided into remimazolam group （group R ）and propofol group （group P ）. During anesthesia induction ，group R was intravenously injected with remimazolam 0.2 mg/kg+sufentanil 0.3 μg/kg+cisatracurium 0.2 mg/kg；group R was intravenously injected with propofol 2 mg/kg+sufentanil 0.3 μg/kg+cisatracurium 0.2 mg/kg. During anesthesia maintenance，group R was intravenously pumped with remimazolam 0.4-1.2 mg/（kg·h）+remifentanil 0.1-0.2 μg（/ kg·min）；group P was intravenously pumped with propofol 4-10 mg/（kg·h）+remifentanil 0.1-0.2 μg（/ kg·min）. Both groups were given intravenous injection of cisatracurium intermittently. The anesthesia depth was monitored during the operation and the pumping speed of remimazolam，propofol and remifentanil was adjusted accordingly. The intraoperative infusion volume ，blood loss ，operation time ， opioid dosage ，and visual analogue scale （VAS）scores at 24 and 72 hours after operation were recorded in 2 groups；at the same time，the levels of T lymphocyte CD 3+，CD4+，CD8+ and NK cells were measured 30 min before anesthesia induction ，24 h and 72 h after operation ；CD4+/CD8+ was also calculated. The incidence of ADR was recorded in 2 groups. RESULTS ：There was no statistical significance in intraoperative infusion volume ，blood loss ，operation time ，opioid dosage ，VAS score at 24，72 hours after operation and the incidence of ADR between 2 groups（P＞0.05）. Compared with 30 min before anesthesia induction ，the levels of CD 3+，CD4+，NK cells and CD 4+/CD8+ ratio in 2 groups at 24 hours after operation were significantly decreased （P＜ 0.05）；compared with group P ，the levels of CD 3+，CD4+ and NK cells as well as CD 4+/CD8+ ratio in group R increased significantly in group R （P＜0.05）. CONCLUSIONS ：For anesthesia maintenance ，the inhibitory effects of remimazolam on perioperative cellular immunity in patients underwent radical mastectomy are poorer than propofol.