The characteristics of performance were compared for two types of pump, peristaltic and infusion-withdrawal, commonly used for localized push-pull perfusion of brain tissue. Guide cannulae were stereotaxically implanted bilaterally in the caudate-putamen complex of the rat at homologous sites in the coronal plane. Consecutive 5.0 min push-pull perfusions were carried out simultaneously with one pump perfusing ipsilaterally while the other pump perfused the contralateral caudate nucleus. 3H-dopamine (DA) diluted with an artificial CSF was used as the radiotracer and was perfused at a rate of 25 microliters/min. Following the collection of 7-8 samples, the brain was fixed, removed, and histological sections taken through the sites of perfusion. Microscopic examination of the perfusion site showed that the circumscribed lesion at the tip of the cannula connected to either pump was generally indistinguishable. A comparison of the values of 3H-DA recovery in samples obtained with the peristaltic and infusion-withdrawal pumps demonstrated that: (1) the respective uptakes of the catecholamine into caudate tissue paralleled one another in most experiments, and (2) the content of 3H-DA in push-pull perfusates recovered from sample to sample varied independently of the pump used. Based on the results of histopathological examination and DA radioactivity values, it is concluded that the peristaltic pump as well as the syringe-driven push-pull pump can yield valid experimental observations which are comparable to one another.