Bone metastases are located most frequently in cancellous bone according to the higher blood perfusion rate. In contrast, pathological fractures are most frequently found in the biomechanically highest loaded parts of the skeleton and are therefore most frequent in the proximal femur end. For definition of impending pathological fracture the Mirels Score should be used today. Because of the short life expectancy of the patients with pathological fractures caused by bone metastases immediate pain relief, function and weight bearing capacity must be achieved. In the proximal femur stabilisation can be performed with a hip tumor prosthesis or, as joint preserving device, a double plate compound osteosynthesis (DPCO). The results of 30 patients treated with hip tumor prosthesis and 30 patients treated with a DPCO of the proximal femur between 1985-1989 were compared. The local complication rate of the tumor prosthesis was significantly higher (16.6% vs 46.6%) due to 11 hip luxations seen in 7 of the 30 patients. The time of hospitalisation as well as the costs of the device are higher for the tumor prosthesis. The functional and subjective results were similar. Only in patients with very advanced carcinoma and a life expectancy under 3 months osteosynthesis without resection of the metastasis should be performed. For this indication only locked nail systems should be used today. We found the best functional results among 134 patients treated between 1982-1989 in our hospital in patients with impending pathological fractures. The functional results as well as the survival time were up to 3 times superior to those of patients with occurred pathological fractures.(ABSTRACT TRUNCATED AT 250 WORDS)