Objective: To evaluate the safety and tolerance of multi-dose ulinastatin (UTI) for injection in Chinese healthy volunteers.Methods This is a parallel, randomized, double-blind, placebo-controlled, multi-dose study.24 health volunteers were randomized into A, B, C three dose groups.In each group, 2 subjects were administrated with placebo and 6 subjects with.Each health volunteer received four doses a day, with interval period of 3 h.The health volunteers in group A, B and C were administrated 6×105, 9×105 and 12×105 U UTI at each dose,respectively.Each subject received the first dose of UTI by intravenous infusion over 30 minutes at a stable rate using an infusion pump, and the following three doses via intravenously drip at a rate of 5×105 U/0.5 h.Adverse events (AEs), vital signs and laboratory tests throughout the study were used to assess the safety and tolerance.Results All the 24 healthy volunteers finished the study.After administration of UTI, 5 cases of FIB with clinical significance occurred in C group and placebo group, other test results were normal or abnormal with no clinical significance.During the trail, no serious AEs were observed.No AEs occurred in the group A and group B.Only 2 cases of slight and mild diarrhea, probably related to the drug, and 1 case of periumbilical abdominal pain, probably unrelated to the drug, were observed in group C (except the placebo group);3 and 2 cases of FIB, probably unrelated to the drug, were observed in group C and placebo group, respectively.All AEs were of grade Ⅰ according to the common terminology criteria for adverse events (CTCAE) version 4.0 and required no medical intervention.Conclusion: Multi-dose (qid) ranged from 6x105 U to 12×105 U of UTI in Chinese healthy volunteers was safe and well tolerant.It is recommended that dose up to 12×105 U (qid) may be tested for the follow-up clinical trials.