A new lanostanoid, ganoderic acid SZ (1), isolated from a lipophilic extract of the fruiting body of Ganoderma lucidum, is a geometric Z-isomer of the known ganoderic acid S (2). The structure of ganoderic SZ (1) was deduced mainly by 1D and 2D NMR studies. During the course of this study, 12 known lanostanoids have also been isolated and characterized.