A pituitary tumor with suprasellar and extrasellar extension was investigated by means of the squash-smear cytologic technique. The dominant cell type was large, round to oval cells, with pale-staining, finely granular cytoplasm. The nuclei of these cells often contained single or multiple inclusions of uncertain nature. There also were cells with eosinophilic cytoplasm, usually collected in small nests. Hyperchromatic "naked" nuclei, in various shapes, were immersed in a homogeneous, faintly staining ground substance. Mitotic figures were detected easily. Cytology of these combined cell types allowed the intraoperative diagnosis of a rather pleomorphic pituitary adenoma.