Due to improved oncological therapeutic procedures with longer survival times, the stabilization of osteolyses and pathological fractures is gaining importance. The proximal femur is often affected by metastases. As femoral stability can be compromised by such bone lesions, stabilization as a palliative measure is indicated to restore function and relieve pain. Besides intramedullary osteosynthesis and endoprosthetic reconstruction, compound osteosynthesis is an alternative method for stabilization of the proximal femur. Between 1994 and 2004, 34 compound osteosyntheses were performed for a tumor-caused lesion compromising mechanical stability of the proximal femur. Of those cases, 22 double-plate compound osteosyntheses and 12 single-plate compound osteosyntheses were performed for 9 pathological fractures and 25 osteolyses. Both techniques provided good primary stability. The average survival time after compound osteosynthesis was 14.2 months (range, 0-72 months). Double-plate compound osteosyntheses showed a lower mechanical failure rate than single-plate compound osteosyntheses (14.3% vs 33.3%) and a higher survival probability after 5 years (76.4% vs 38.6%). No surgical revision was required due to perioperative complications in any case. We conclude that reliable stabilization of extensive osteolyses and pathological fractures of the proximal femur can be achieved with compound osteosynthesis. Our data suggest that double-plate compound osteosyntheses is a more favorable technique than single-plate compound osteosyntheses based on a lower rate of mechanical failure and higher survival probability.