We present a case report demonstrating the experience of the department of pediatric orthopaedics of the University Orthopedic Hospital at Sofia Medical University in the treatment of an intertrochanteric proximal femoral fracture in a child with osteopetrosis. We performed open fracture reduction with stable 120° LCP (Locking Compression Plate) Pediatric hip osteosynthesis. Fracture consolidation and ability to walk without crutches was achieved in a half a year. The presented case is the first for Bulgaria. There are still no publications in the world literature on application of such osteosynthesis in marble bone disease.