A new diosgenin derivative designated denfigenin has been isolated from the petrol extract of the whole plant Dendrobium fimbriatum, along with diosgenin and defuscin (n-triacontyl p-coumarate). Denfigenin was shown to be (25R)-22α-O-spirost-5-ene-3β,16α,17α-triol mainly based on 1H and 13C NMR spectral studies. Its molecular conformation has also been discussed. © 1992.