Minute fresh tissue fragments from 20 pituitary adenomas and 18 oligodendrogliomas were crushed between two glass slides and stained with hematoxylin and eosin for cytologic examination. These two tumor types displayed distinctive cytologic features that may permit their correct identification. Pituitary adenomas were characterized by single and clustered tumor cells with monomorphic, round or vesicular nuclei that were commonly denuded of cytoplasm. Rare well-preserved tumor cells showed well- or ill-defined, variable and granular cytoplasm. Oligodendrogliomas showed cells with monomorphic or slightly pleomorphic nuclei and scant, fibrillary, wispy cytoplasm, commonly arranged in clusters or around circular and empty spaces.