The catecholamine and nucleotide content of chromaffin granules from bovine adrenal medulla was analyzed both qualitatively and quantitatively. Nucleotides were examined by separation on anion exchange high pressure liquid chromatography and ultraviolet absorption, as well as by anion exchange thin-layer chromatography and luciferin-luciferase light emission analysis. CPATHECHOLAMINES WERE QUANTIFIED VIA AUTOMATED CONTINUOUS-FLOW ANALYSIS USING FLUORESCENCE. We found the average catecholamine/ATP ratio to be 8.2:1 with an SD of 1.98 and an SE of 0.50 for 16 separate glands. Relative percentages of epinephrine and norepinephrine were found to be 79.8 and 20.2, respectively. The granules contained 80.9% ATP, 12.3% GTP, and 6,8% UTP, as well as detectable amounts of ADP, AMP, GDP, and UDP. If we accept the catecholamine/ATP ratio of 4:1 proposed by Hilliarp earlier, then those catecholamines constituting the remainder of our ratio of 8.2:1 should represent a nucleotide-unassociated pool. In view of recent evidence of a direct agonistic function of nucleotides, we propose that the granule-associated nucleotides may act locally as coagonists with certain biogenic amines, and may additionally provide acirculating pool of purines and pyrimidines for use by the heart and lungs.