Six lanostane-type triterpene acids were isolated from the fruiting bodies of Piptoporus betulinus. They were identified as polyporenic acids A (1) and C (2), three derivatives of polyporenic acid A (3-5), and a novel compound, (+)-12 alpha,28-dihydroxy-3 alpha-(3'-hydroxy-3'-methylglutaryloxy)-24-methyllanosta-8,24(31)-dien-26-oic acid (6). All these compounds suppressed the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema on mouse ears by 49-86% with a 400 nmol/ear application.