Procyanidins are known as condensed tannins and/or oligomeric flavonoids, and are present in many edible plants and show interesting various biological activities. We previously developed and reported a simple and versatile method of synthesizing procyanidin oligomers consisting of (-)-epicatechin and (+)-catechin. Here, we report the structure activity relationships (SAR) between the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and Mail lard reaction inhibitory activities of various procyanidin oligomers synthesized, including dimers, trimers, tetramers, pentamers, 3-O-substituted oligomers, and other artificial oligomers.