PURPOSE: The purpose of the current study is that CT can predict peroneal tenosynovitis in the intraarticular calcaneal fracture. MATERIALS AND METHOD: Sixty five calcaneal fractures in 55 patients were evaluated with CT scan. The follow-up period after operation was averaged 19 months (ranging from 4 to 79 months). A classification for peroneal tendon injury was developed, based on CT scan. RESULTS: Of the 65 intraarticular calcaneal fractures, the incidence of peroneal tenosynovitis were 14 cases(26%)[open reduction and internal fixation group 7/43(16%), Essex-Lopresti group 7/22(32%)]. According to the author's classification, the incidence of peroneal tenosynovitis among open reduction and internal fixation subgroup was followed ; type I was none(0/4), type II 11%(2/19), type III 20%(3/15) and type IV 40%(2/5) respectively(p=0.074). The incidence of peroneal tenosynovitis among Essex-Lopresti subgroup was followed ; type I was none(0/4), type II 16%(1/6), type III 33%(3/9) and type IV 100%(3/3) respectively(p=0.009). CONCLUSION: CT can be used to evaluate the status of the peroneal tendon as well as to predict the development of peroneal tenosynovitis. The open reduction and internal fixation in type III and IV is preferable to achieve a alignment of peroneal tendon and a accurate reduction of subtalar joint.