This paper provides some historical aspects on the research and development of Humulin (rDNA origin), the first human health-care product derived from rDNA technology more than a decade ago. Also referred to as biosynthetic human insulin, Humulin is currently produced via the human proinsulin route, using an Escherichia coli fermentation process. The authenticity, high purity, and safety of BHI has been investigated and verified by a complex battery of analytical and physicochemical methods. The daily treatment of more than two million diabetic patients worldwide with this rDNA human insulin not only demonstrates the value of rDNA technology in providing an important medical product, it is assurance that diabetic patients will have unlimited supplies of this vital hormone as well as potential analogue refinements.