Seven patients with metastatic tumour in the pituitary-hypothalamic axis were investigated by MRI. The main clinical problems were diabetes insipidus (5 cases) and general pituitary dysfunction (2 cases). No patient had visual or oculomotor symptoms. In 6 of the 7 patients the primary malignant tumour was known, but no patient had symptoms from the primary tumour; 1 had symptoms from metastases in locations other than the pituitary gland. In one patient no primary tumour was known. MR detection of a second, clinically silent, 5 mm lesion in the posterior cranial fossa initiated the search for primary tumour. MRI showed purely suprasellar tumours in 3 patients and intra- and suprasellar tumours in 4. The latter were dumbbell lesions with only a small bridge of tissue connecting the intra- und suprasellar portions. Six of the 7 suprasellar tumours seemed to be in the infundibular recess of the third ventricle; in 5 the infundibulum was visible as an enhancing linear structure at the postero-inferior border of the tumour. The pituitary fossa was normal in all cases.