Pituitary ablation by the injection of alcohol through a transphenoidal needle has been practised for a number of years. In order to reduce the complications resulting from the spread of alcohol to neighbouring structures, a cryoprobe has been constructed which can be passed up through the needle into the gland and a series of localised lesions produced. The degree of pain relief is as good if not better than that obtained with alcohol. Only one instance of temporary blurring of vision resulted and hormonal disturbances were not seen. No difference was observed between the results obtained from the treatment of hormone-dependent and hormone-insensitive tumours. Pain caused in one patient by a benign tumour was unsuccessfully treated.