Cytology as a diagnostic tool has played a major role in the management of diseases affecting domestic mammals for over 20 years. It has also become a valuable diagnostic tool in the evaluation of nondomestic or the so-called "exotic" animal patients, such as small mammals and the lower vertebrates. Common cytologic specimens used to evaluate the exotic animal patient include aspirates of masses and organs, imprints of biopsy material, tracheal wash samples, aspiration of abdominal or coelomic fluid, and fecal smears. In general, the same cytologic sample collection and preparation techniques used for domestic mammals also apply to exotic animal patients. The interpretation of the cytology specimen is generally the same as that of domestic mammals.