Unicameral bone cysts are benign solitary lesions that occur in the first two decades of life and with a greater frequency in the humerus and femur. The cyst is usually asymptomatic unless a fracture or impending fracture is present. The traditional method of treating unicameral cysts has been curettage with bone graft or steroid injection. Also, pathologic fractures in the calcaneus, unlike in other bones, are reported especially in the children to be nonexistent. In general, closed treatment was recommended for most of the calcaneal fractures in children, but suggested open reduction when joint displacement was severe. We report a case of displaced intraarticular fracture of the calcaneus with unicameral bone cyst in a child treated by classic curettage, allograft and open reduction with screw fixation.