The findings in 50 patients examined by computed tomography (CT) of the pituitary fossa are described. The appearances in 43 were judged to be abnormal, four were normal and three were 'doubtful'. Abnormal features included deviation of the pituitary stalk (seven), localised increased enhancement after intravenous injection of contrast medium (18) and extrasellar extension of tumour (11). The CT scans enabled diagnoses of pituitary microadenoma, empty sella and combinations of the two to be made. Modern CT scanners (third or fourth generation) provide detailed information enabling the optimum assessment and treatment of sellar and parasellar lesions.