The role of catecholamines in regulation of episodic GH secretion was investigated in the male rat. Administration of alpha-methyl-p-tyrosine (alpha-MT; 250 mg/kg ip) caused significant suppression of GH bursts and resulted in marked elevation of plasma PRL. Intravenous administration of apomorphine (.03 and .1 mg/kg) had no effect on decreased GH levels, whereas clonidine (150 micrograms/kg) restored GH secretion. Apomorphine significantly reduced PRL levels in alpha-MT-treated rats whereas, clonidine resulted in a further increase in PRL.