Avulsion fractures of the calcaneal tuberosity are rare injuries in extraarticular fractures of the calcaneus and were resulted from a separation of a shell of the posterior portion of the os calcis due to the pull of the Achilles tendon. Importance of anatomic reduction for the restoration of functional length of Achilles tendon were emphasized by many authors in the treatment of the fractures. The purpose of this study is to evaluate the results of operative treatment in avulsion fractures of the calcaneal tuberosity and to analyse the results in accordance with various prognostic factors. This article has reviewed a series of 6 avulsion fractures of calcaneal tuberosity, treated from March 1991 to November 1996. The results were as follows ; 1. In case of avulsion fracture of os calcaneus, open reduction and internal fixation was needed for the accurate anatomical reduction and maintenance of firm internal fixation. 2. The method of operative treatment was not significant influencing factor on the treatment result, however, it is more convenient to fix when cannulated screws were used because of the compressive effect on the fracture site. 3. Complications included superficial skin necrosis in one case, which resulted from the compression of bony fragment in case of avulsion fracture and another, wire fixation failure because of bone resorption resulted from wide soft tissue dissection.