The principal end-use of azodicarbonamide (ADA) is as a blowing agent in the rubber and plastics industries. It is used in the expansion of a wide range of polymers, including polyvinyl chloride, polyolefins, and natural and synthetic rubbers. Azodicarbonamide has in the past been used in the United Kingdom and Eire (but not other European Union member states) as a flour improver in the bread-making industry, but this use is no longer permitted. In vitro azodicarbonamide decreases the intracellular pool of deoxyribonucleotide and thymidine phosphorylation. Ribonucleotide reductase is a potential target of azodicarbonamide. Azodicarbonamide (ADA) represents a new compound that inhibits HIV-1 and a broad range of retroviruses by targeting the nucleocapsid CCHC domains. Vandevelde et al. also recently disclosed that ADA inhibits HIV-1 infection via an unidentified mechanism and that ADA was introduced into Phase I/II clinical trials in Europe for advanced AIDS. These studies distinguish ADA as the first known nucleocapsid inhibitor to progress to human trials and provide a lead compound for drug optimization. Phase-II development is ongoing in Spain for HIV infections.