Osteoidosteomas are common bone tumours in childhood. Frequently they occur in the long bones of the lower extremities, less frequent in the humeri, phalanxes or the axial skeleton. The tumour is benign and noninfiltrative. Metastases do not occur. Typical complaints are nightly pain attacks, which are relieved by nonsteroidal antiinflammatory drugs. On X-ray, the classic finding is a small radiolucent area surrounded by sclerotic bone in the cortex. Surgical excision is often recommended, providing the possibility for a histological diagnosis. Therapeutic alternatives are percutaneous coagulation of the nidus by alcohol or laser, thermo-coagulation or high-frequency radioablation. Spontaneous remissions are well documented. Therefore the decision to wait and see and to treat with antiinflammatory medication is a considerable therapeutic option. We present two patient with an ostoidosteoma in the proximal femur. One of them underwent an unsuccessful trial for surgical extirpation and histological examination but afterwards developed a severe hip contraction with scoliosis. In the case of the other patient a primary operation was abandoned. Pain was completely controlled upon treatment with nonsteroidal antiinflammatory drugs in both patients. The contractions also disappeared completely upon physiotherapy. Serial MRI showed a significant regression of the inflammatory reaction in one case and the disappearance of the tumour in the other one. In conclusion, pharmacomedical therapy can be recommended, if the diagnosis is doubtlessly and a close follow up is established. The risk of anaesthesia and surgical treatment should be weighted against the risk of nonsteroidal antiinflammatory drug treatment.