Author's Organization：National Institute of Hygienic Sciences College of Agriculture and Veterinary Medicine, Nihon University National Institute of Hygienic Sciences
The structure of helicobasidin, a major pigment of Helicobasidium mompa TANAKA, was proved to be (S)-3-methyl-2, 5-dihydroxy-6-(1, 2, 2-trimethylcyclopentyl) benzoquinone (IV).
