Hamartomas of the tuber cinereum are tumour-like collections of normal tissue in abnormal location. They are benign lesions with slow or absent growth and without any tendency to neoplastic evolution. Due to their neurosecreting properties they usually cause precocious puberty. Further neuroendocrine disturbances, seizures, or psychoneurological symptoms may be associated in some cases. Cisternography and CT are the most conclusive radiologic procedures in all cases. The typical feature is a well circumscribed round-shaped isodense soft tissue mass without contrast enhancement. Usually the tumour is small, rarely exceeding 2 cm. in diameter. If CT diagnosis is not conclusive, examination in the coronal plane or CT cisternography are recommended. Although CT does not permit a histological diagnosis the clinical and radiological features together are sufficient to make a highly suggestive diagnosis. The treatment of choice is medical therapy. Surgery should be restricted to those tumours which damage surrounding structures by their size and cause other symptoms than precocious puberty.