Abstract: We report the short- and mid-term results in six patients (seven feet) affected by markedly comminuted intra-articular calcaneal fractures (Sanders type IV), treated by primary subtalar arthrodesis. The average age at surgery was 40 years. In all patients, arthrodesis of the subtalar joint was performed using a limited lateral approach to the calcaneus; it was stabilised with two or three cannulated screws. No patient had a preliminary reduction and internal fixation of the fracture. The time from injury to surgery averaged 20 days because all of the patients had associated visceral and/or other skeletal injuries. All of the patients were followed up clinically and radiographically 2 times, at an average of 12 months and 53 months after surgery. At the short-term follow-up, the mean AOFAS score was 70 points; the X-rays showed a complete fusion of the subtalar joint in all seven feet, without any sign of osteoarthritis of the calcaneo-cuboid and the talo-navicular joints. In all cases, an altered shape of the calcaneus was present. At the mid-term follow-up, the mean AOFAS score increased to 85 points; in one patient, radiographic signs of osteoarthritis of the calcaneo-cuboid and the talo-navicular joints were present and, in another patient, only talo-navicular joint was present, although both patients were free from pain. The difference between the two AOFAS scores was statistically significant. We believe that primary subtalar arthrodesis performed for markedly comminuted Sanders type IV calcaneal fractures yielded good mid-term results, and it is especially indicated when surgical treatment is delayed for whatever reason. A preliminary open reduction and internal fixation to restore the normal height of the calcaneus before performing the subtalar arthrodesis, as suggested by several authors, does not seem indispensable to obtain good clinical results. [Copyright &y& Elsevier]