PURPOSE: Antithrombin (AT) is one of the most important natural inhibitor of coagulation, and patients with disseminated intravascular coagulation (DIC) almost invariably have an acquired deficiency of anti thrombin. The aim of our study is to evaluate the effect of replacement of antithrombin in patients with DIC and low plasma antithrombin levels after trauma or surgery. METHODS: We conducted a retrospective trial in patients with documented DIC. The patients received a loading dose of AT (1,000 IU) initially, followed by 2,000 IU per day for 2-5 days. The complete blood count, the DIC profiles (fibrinogen, FDP, PT, PTT), the AT level, and the biochemial and clinical responses were evaluated. RESULTS: A total of 19 patients with DIC due to trauma and/or postsurgical complications were enrolled. One patient received AT on two separate occasions, so a total of 20 episodes of AT infusion were evaluated. The ratio of males to females was 15:4, and the median age was 56 (range: 6-82). Compared to the initial laboratory findings, the levels of AT, PT, and PTT, as well as the platelet count were significantly improved after the infusion of AT. Biochemical response was achieved in 14 (70%) episodes, but a beneficial clinical effect was obtained in only 8 (40%) episodes. CONCLUSION: Antithrombin concentrate may improve the general status of patients with DIC after trauma and/or surgery. More, extensive clinical trials are required in order to confirm this.