Curvularin is a 12-membered macrocyclic lactone incorporating a resorcinyl moiety, produced by a number of fungal species including Curvularia, Penicillium and Alternaria. Curvularin exhibits a distinctly different biological profile to the structurally similar resorcylic acid lactones such as the zearalenones, radicicol and LL Z1640-2. Curvularin inhibits cell division by disrupting mitotic spindle formation and is known to be phytotoxic. More recent investigations have shown that curvularin is a highly selective transcription-based inhibitor of iNOS-dependent NO production, acting on the Janus tyrosine kinase-STAT pathway. This action offers an approach to the development of drugs inhibiting iNOS overproduction associated with NO pathophysiology.