Osteosarcoma is the most common form of primary malignant bone tumour that occurs during childhood and adolescence. The incidence of new diagnoses peaks in the second decade of life. The metaphysis of the long bones is the site of predilection, and, in declining order, it commonly involves distal femur, proximal tibia, and proximal humerus. The proximal fibula is a relatively rare site for osteosarcoma. We are reporting a case of osteosarcoma of proximal fibula in a 17-year-old male child and discuss the difficult aspects of diagnosis and management.