Bone metastases are frequently one of the first signs of disseminated disease in cancer patients. In the majority of patients, the primary tumour originates from the breast, prostate or lungs. Even although the prognosis is serious, a proportion of the patients will survive for several years and will thus require active treatment. More than 25% of the patients have no symptoms whereas pain dominates in the remainder. Frequent complications are pathological fractures, hypercalcaemia and spinal cord compression. Normally, the diagnosis can be established from the clinical picture compared with a series of laboratory analyses, x-ray investigations of the skeleton and bone scintigraphy. As treatment is mainly palliative, the purpose is primarily relief of pain, prevention of fractures and ensuring a reasonable functional level. The therapeutic possibilities comprise local treatment in the form of surgery and irradiation and also systemic treatment in the form of chemotherapy, endocrine therapy and possibly diphosphonates. of these, irradiation still plays the most important role. About 80% of the patients respond to treatment and, after 12 months, 50-70% of the surviving patients will still be free from pain. Only few randomized investigations are found in the literature available and the criteria of response are, in general, difficult to interpret. There is, therefore, a great requirement for more clinically controlled investigations which assess the efficacy of the numerous therapeutic possibilities.