a-Amyrin, esterified germanicol and /t-amyrin have been identified as major constituents of E. pulcherrima latex. In freshly tapped latex only a part of the latex triterpenes were synthesized from acetate and mevalonate. By feeding 14C sugars or acetic acid to intact plants and subsequent analysis of tapped latex is synthesis of all the latex triterpenes could be demonstrated. Three other Euphorbia species were studied for comparison and the results obtained are discussed. A dual mechanism of latex triterpene synthesis and a tentative model of latex particle formation is proposed.