A retrospective study of the surgical treatment of 166 metastatic lesions of the humerus and femur in 147 patients was performed. There were 106 women and 41 men whose average age was 62 years. Two-thirds of the patients were treated for complete fractures, while one-third were treated for impending fractures. Breast, lung, and kidney carcinoma accounted for the majority of the primary lesions. One-half of the patients died within nine months of surgery, while one-quarter were alive 19.1 months after surgery. The patients with breast cancer had the best prognosis, while the patients with lung cancer had the worst. The probability of implant failure increased linearly with time to 33% at 60 months. The probability of failure for the femoral lesions was greater, with 44% at 60 months. The average survival in the patients with failed fixation in the femoral lesions was 34.5 months with a mean interval to failure at 17.7 months. The failure rate was high (23%) in proximal femoral lesions treated with a compression screw or nail plate. Common reasons for failure included poor initial fixation, improper implant selection, and progression of disease within the operative field. Bone cement augmentation should be used with the fixation device when possible. Complications due to hip-screw cut-out from the head may also be reduced by applying bone cement around the screw threads.