Aortic organ and cell culture systems have made important contributions to the understanding of the synthesis and accumulation of elastin in arterial tissues. However, methods used to quantitate production of elastin have been diverse, and evaluations of different culture conditions have not been made. In this study we describe a convenient and reproducible organ culture system for the assay of insoluble elastin synthesis. Under optimum incubation conditions, insoluble elastin is produced in organ culture at rates approximating in vivo accumulation rates. The assay is stable under a wide variety of incubation conditions, although elastin production is sensitively inhibited by acidification of the incubation medium. Alterations in intracellular calcium concentration had little effect on elastin production. In contrast, manipulations of sodium ion concentration, including treatment with ouabain or monensin, depressed elastin production. Except at high doses, pharmacological or humoral agents, including non-steroidal anti-inflammatory agents, alpha and beta adrenergic agonists, cyclic nucleotides, theophylline or aminophylline, and histamine, generally had only small effects on elastin production in this organ culture system.