Two male and one female patient, aged 64, 70 and 51 respectively, were surgically treated for pathological fracture of the proximal femur without preoperative biopsy. In contrast to their benign radiological diagnosis, all three patients were finally diagnosed as having a malignant primary bone tumour. The proximal femur is the primary location of pathological fractures in the appendicular skeleton. Metastases to bone are the most common cause of a destructive lesion of the skeleton in an adult. Although rare, a primary bone tumour must be included in differential diagnosis of a pathological fracture. A systematic diagnostic strategy is critical to avoid complications that make curative treatment impossible. A solitary bone lesion seen on radiography should never be assumed to be a bone metastasis. Without further diagnostic research, surgical treatment for a pathological fracture should never be commenced before a definitive diagnosis is made.