Objective To investigate the functions and feasibility of clinical applications of frozen-thawed platelet without dimethyl sulfoxide (DMSO) elution. Methods From January to December 2015, a total of 60 bags (200 mL/bag) of cryopreserved platelets which were prepared and saved by Dongying Central Blood Station of Shangdong Province were included into this study, by simple random sampling method. These 60 bags of cryopreserved platelets were thawed and included in thawed original platelet group (n=60). After mixing 10 mL platelet of thawed original platelet group with 30 mL fresh frozen-thawed plasma according to the volume ratio of 1∶3, the new gained ones were included into the mixed platelet group (n=60). And a total of fresh platelet which were collected by our blood station in the same period were included into control group (n=60). The quality of above-mentioned frozen-thawed platelets, fresh liquid platelets, and fresh frozen-thawed plasma met the relevant regulations in Quality Requirements for Whole Blood and Blood Components (GB18469-2012). A total of 150 patients who received frozen-thawed platelets without DMSO elution transfusion in the Second People′s Hospital of Dongying at the same period were randomly selected as blood transfusions reaction observation objects, by using simple random sampling method. Three groups of platelets were detected with thrombelastogram and coagulation time after recalcification, so as to compare the platelet coagulation function in each group. A retrospective analysis was carried out on the transfusion reactions of 150 patients after transfusion with frozen-thawed platelets without DMSO elution, and the platelet counts in peripheral blood were compared before and 1, 24, 48 and 72 h after transfusion, so as to analyze the clinical application of frozen-thawed platelets without DMSO elution. The study protocol was approved by the Ethical Review Board of Investigation in Human Being of the Second People′s Hospital of Dongying. Informed consent was obtained from all participants. Results ① Thrombelastography coagulation index (CI) of mixed platelet group was 2.5±0.2, which was higher than that of 1.0±0.1 in control group, and that of 0.9±0.2 in thawed original platelet group, and the differences were statistical significant (t=16.69, 23.02; P<0.05). ② The coagulation time after recalcification of mixed platelet group, thawed original platelet group and control group were (6.5±0.5), (9.0±0.75), (11.0±1.08) min, respectively. There was significant different of coagulation time after recalcification among these three groups (F=27.38, P<0.05). Compared with control group, the coagulation time after recalcification of platelet in thawed original platelet group was obviously shortened, and the difference was statistically significant (q=-7.38, P<0.05). Compared with control group and original platelet group, the coagulation time after recalcification of platelet in mixed platelet group was also obviously shortened, and the differences were statistically significant (q=-3.36, -2.29, P<0.05). ③ In this study, 150 patients were transfused with a total of 319 therapeutic dose of frozen-thawed platelet without DMSO elution, and no adverse transfusion reaction were found in them. Compared with pre-transfusion, the platelet count was increased by (7.6±1.1)×109/L of 48 h after transfusion, the increase value was lower than those of (16.3±2.5)×109/L and (13.5±2.5)×109/L at 1 and 24 h after the transfusion, and the differences were statistically significant (t=-24.87, -25.92, P<0.05). Conclusions The coagulation function of the mixture of frozen-thawed platelet without DMSO elution and fresh frozen-thawed plasma (the volume ratio of 1∶3) was significantly increased, its quick hemostasis effect was good. No adverse transfusion reaction was found of clinical transfusion of frozen-thawed platelet without DMSO elution, which could meet the need of acute hemostasis. Key words: Dimethyl sulfoxide; Blood preservation; Blood platelets; Plasma