Sterols from ascocarps of Tuber(truffle) and Terfezia species were identified by gas-liquid chromatography, gas chromatography-mass spectrometry, and 1H nuclear magnetic resonance, and the structure of brassicasterol from the yeastlike cells of Taphrina deformans confirmed 1H nuclear magnetic resonance, and the structure of brassicasterol from the 1.2 to 2.3 .mu.g/mg dry weight. Ergosterol was the principal sterol of Tuber species which also contained 28-44% brassicasterol depending on the species and source of the sample. Terfezia sp., on the other hand, contained about 98% brassicasterol with only small amounts of ergosterol. Brassicasterol is common to several families of the subdivision Ascomycotina, and to our knowledge has not been reported for a nonascomycetous species.