Versican is a large chondroitin sulfate proteoglycan (CSPG) initially identified in cultured human fibroblasts. Previous studies have shown that there is a versican-like molecule in cultured monkey smooth muscle cells. In this study, we have cloned and sequenced the large CSPG from cultured monkey smooth muscle cells, fetal and juvenile monkey aorta, and human fetal aorta. The cDNA sequence from human fetal aorta is completely homologous to the human fibroblast versican. We obtained 2.5 kb of cDNA sequence from monkey aortic RNA and cultured monkey smooth muscle cell RNA. This sequence covers three distinct domains of versican (hyaluronic acid binding domain, glycosaminoglycan attachment domain and protein binding domain) and demonstrates over 90% homology to the human versican sequence. In situ hybridization histochemistry indicates that the versican RNA transcript is located in the epithelium throughout the tunica media of the aorta. Western blot analysis and immunohistochemistry also confirm the presence of versican in human and monkey aorta.