Growth hormone (rGH) and prolactin (rPRL) secretory profiles were obtained before and after treatment with a dopamine receptor blocking agent, (+) butaclamol, in 10 male rats chronically implanted with right atrial cannulae. Mean rGH plasma concentrations, determined by planimetry, were reduced (202 ± 20 ng/ml vs. 135 ± 20 ng/ml, P < .01), but the basic configuration and periodicity of rGH secretory bursts were unaltered. Mean rPRL plasma concentrations were elevated (11.1 ± 2.1 ng/ml vs. 65.5 ± 8.1 ng/ml, P < .0005), but rPRL episodic secretion was still apparent. It is concluded that dopaminergic neurons have a minor role in facilitating episodic rGH secretion. Furthermore, persisting episodic rPRL secretion in rats administered a dopamine antagonist suggests that rPRL feedback inhibition does not inactivate the neural mechanism generating episodic rPRL secretion.