During the search for natural substances with PPAR-gamma agonistic effect, unique polychlorinated compounds named chlorophellins A-C have been isolated together with the known compound, drosophilin A, from the methanolic extract of the fruiting body of the fungus Phellinus ribis. Their structures were assigned on the basis of NMR and mass spectrometric analyses. Chlorophellin C of compounds tested exhibited the most potent PPAR-gamma agonistic effect and was comparable to rosiglitazone, a well-known PPAR-gamma agonist that has been used for the therapy of type 2 diabetes.