Stimulation of chromaffin cells in culture with 1, 1-dimethyl-4-phenylpiperazinium (DMPP) or depolarizing concentrations of K+ results in a significant secretion of high and low molecular weight enkephalin-like peptides (ELPs) into the culture medium. Bio-Gel P-10 chromatography was used to characterized the ELPs in the extract of chromaffin cells and in culture media before and after stimulation. DMPP (50μM) stimulation produced a significant secretion of primarily low molelcular weitht (3-kOa)ELPs whereas 56 mM K+ caused a secretion of both the high and low molecular weights ELPs. Subsequent to the secretion of these ELPs the expected decrease in the content of cellular low molecular weight peptides was not observed. This suggests that stimulation of chromaffin cells by either an action on nicotinic receptors or by membrane depolarization enhances processing of ELPs. Our results support the hypothesis that specific stimuli bring about the secretion of ELPs of differing molelcular weight.