Symptomatic pituitary metastases are uncommon and may be difficult to differentiate from pituitary adenomas. In order to ascertain the incidence of pituitary tumors in cancer patients and to characterize the clinical presentation of pituitary metastases, we reviewed the clinical experience with these tumors at Memorial Sloan-Kettering Cancer Center (MSKCC) during the period 1976-1979 and a recent series of 500 consecutive autopsies in which the pituitary fossa and gland were examined. In the clinical series, a histologic diagnosis was made in three of five patients. Radiologic evaluation, including polytomography and computed tomography, did not reliably distinguish metastasis from adenoma, but the clinical syndromes were distinctive. In the autopsy series, pituitary metastases were found in 3.6% of cases, pituitary adenomas in 1.8%.