The first examples of intramolecular addition of primary amidyl radicals to olefins are described. Amidyl radicals were generated from N-(phenylthio)amides in refluxing benzene using a catalytic amount of 2,2′-azobis(isobutyronitrile) (5 mol%) and tributyltin hydride (~2.2 equiv.). The resulting yields of cyclic products ranged from 63% to 85%.Key words: radical cyclization, amidyl radicals, nitrogen heterocycles.