Due to a rise in life expectancy as well as improved adjuvant and diagnostic measures the incidence of clinically symptomatic metastases has significantly increased. In terms of indication and operative technique in the treatment of these lesions the biologic age, general condition, diagnosis, stage and activity of the disease and the patient's prognosis are highly important. Different techniques of joint replacement have been described to treat patients suffering from metastatic disease of the periacetabular region, being resistant to any kind of adjuvant therapy. From 1977-1996 21 patients with a periacetabular lesion received a tumor prosthesis following internal hemipelvectomy (average age 60 years; average survival 23.1 months). Perioperative complication rate was 42%, functional results were good (n =), fair (n = 9) and poor (n = 2). Mobilisation and analgesia are the most important therapeutic goals. The quality of the patient's life postop is the major point.