From the ethyl acetate extract obtained from the methanol extract of the mushroom Pleurotus sajor-cajú, ten compounds conforming the triterpenic fraction were isolated by means of chromatographic techniques like CC and PTLC, and were identified by their MS as: Ergosta-2,5,7,9(1 l),22-pentaene, Ergosta-5,7,9(1 1),22-tetraen-ß-ol, Ergosta-5á,8á-epidioxy-6,22-dien-3R-ol (ergosteryl peroxide), Ergosta-5,7,22-trien-3R-ol (Ergosterol), Ergosta-7,22-dien-3R-ol, 19-Norergosta-5,7,9,22,tetraen-ß-ol (Neoergosterol), Ergosta-7-en-3R-ol, Ergosta-3ß-5á,6ß-trihydroxy-7,22-diene (Cerevisterol), Ergosta-4,6,8(14),22-tetraen-3-one and Ergosta-4,6,15(16),22-tetraen-3-one. Likewise, three fatty acids were found and identified as palmitic acid, linoleic acid and stearic acid.