The recent data on the pathways of carotenoid biosynthesis, which resulted in revision of the ear lier concepts, are analyzed. Trisporoid diversity and their role in the sexual process of mucoraceous fungi, resulting in formation of sexual cells (zygospores) are discussed. Special attention is paid to the role of trisporic acids in carotenogenesis of combined culture of the (+) and (-) strains, in which zygospores are not formed.