A large number of novel fatty compounds have been synthesized by catalytic C,C-bond forming addition reactions to the C,Cdouble bond of unsaturated fatty compounds. Radical reactions such as the solvent-free addition of -halocarboxylic acid esters initiated by electron transfer, e.g., from copper to give fat-derived -lactones are described as well as Lewis acid-induced electrophilic addition reactions yielding new oleochemicals such as alkyl-substituted 4-chlorotetrahydropyrans, primary homoallylic alcohols, -, -unsaturated ketocarboxylic acids and Diels-Alder addition products. New catalysts as, e.g., ligandmodified rhodium catalysts for the hydroformylation and heterogeneous boron-modified rhenium catalysts for the olefin metathesis have been developed. The addition of C-nucleophiles such as dimethylmalonate and nitromethane is possible by palladium-(0)catalyzed additions to unsaturated fatty compounds after conversion of the electron-rich to an electron-poor double bond. More than fifty literature articles are reviewed.