Abstract: The steroid sapogenin constiruents of dioscoreaceous and agavaceous plants are re- ported.In dioscoreaceae, according to our investigations the following 6 species are found rich in diosgenin: 1. Dioscorea altheaoides R. Knuth......................... 2.0-2.3% 2. D. deltoidea Wall..................................... 1.8-2.4% 3. D. deltoidea Wall. var. orbiculata Prain et Burkill........ 5.2-5.4% 4. D. panthaica Prain et Burkill ........... ................ 1.7-2.3% 5. D. zingiberensis C. H. Wright........................... 3.4-3.9% 6. D. sP. nov. (collected in Lu-Shui, Yunnan)............. 1.7-2.0% The Dioscorea collettii Hook. f. contains about 1.7% total sapogenin, the main con- stituents are diosgenin and only a little yamogenin can be isolated. In Agavaceae, the sapogenins have been isolated and identified from the seeds of Agave amercana L. as neotigogenin, hecogenin and kammogenin, but the leaves of Agave americana L. var. marginata Hook. are only found to contain hecogenin and 9-dehydrohecogenin. In the rhizome of Poliantbes tuberosa L, besides that the hecogenin has been identified by Li Zhen-su (李振肃), tigogenin and 9-dehydrohecogenin are new found in the present in- vestigation.