Synthetically useful radical reactions mediated by Et3B are described. An addition of catalytic amount of Et3B to a solution of triphenylstannane, triphenylgermane, or benzenethiol in toluene promotes the effective formation of the corresponding triphenylstannyl, triphenylgermyl, or benzenethiyl radical, respectively. Topics are (1) Et3B induced radical addition of R3SnH to acetylenes and its application to cyclization reaction, (2) Et3B induced stereoselective radical addition of Ph3GeH to acetylenes and its application to isomerization of olefins, (3) Et3B induced radical addition of thiols to acetylenes, (4) A facile reduction of dithiocarbonates with n-Bu3SnH-Et3B, (5) Et3B induced hydrodehalogenation of organic halides by tin hydrides, and (6) Et3B-mediated Reformatsky type reaction and three component coupling reaction of alkyl iodides, methyl vinyl ketone, and carbonyl compounds.