Objective:To observe the effect of transplantation of rat islets which cultured in hypothermia microgravity rotary cell culture system(HRCCS) on rats with diabetes mellitus.Methods :The isolated and purified rat islets were divided into three groups: Temperature (37 ℃)culture for 21 days in flaskculture (control group); temperature(37 ℃)culture for 21 days in RCCS (experimental group1 E1); after low temperature (26 ℃)culture for 14 days in HRCCS, then temperature(37 ℃)culture for 7 days in RCCS (experimental grop 2, E2). Survival rate of islets in three transplanted groups was measured by AOPI doublestaining. Cultured islets were identified by dithizone (DTZ) staining, and insulin contents of different culture liquids were measured by radioimmunoassay. Then the cultured islets was implanted into rat recipients and the transplantation effect was observed for 10 weeks.Results:Survival rate of islants in group E2 (67.4±4.6%) was higher than that in group E1 (50.3± 3.5)% and control group (28.1±3.3)% (all P＜0.05). The insulin content and insulin stimulation index in group E2 were higher than those in and group E1 and control group. The survival rate of islets in group E2 (67.4±7.6)% was higher than that in group E1 (28.1±3.3)% and control group (50.3±3.5)% (all P＜0.05). Transplantation of group E1 and E2 islets into diabetes rats coulde restored blood glucose to normal in all recipients within one week, and all recipients maintained normal glucosetolerant curve throughout the observation time. But the effect of group E2 islets transptation on didabetes rats was better than that in group E1 islets transplation; and the effect of control group islets transplantion for controlling blood glucose is not so good. Conclusions:Rat islets cultured in 26℃microgravity rotary cell culture system(26℃RCCS) could improve the effect of islet transplantation.