In addition to known compounds, the aerial parts of E. semiperfoliata afforded an abietanolide (3), 13 jatrophane polyesters (4-9, 12, 14-19), two 4-deoxyphorbol diesters (23, 24), and a pair of epimeric diterpenes (21, 22) with a novel carbon skeleton, which was named euphoperfoliane. Structures were determined by spectroscopic analysis, and the main conformational features of jatropha-6(17),11-dienes are discussed in detail. The obtained isolation yield of several jatrophanes was unprecedented within the spurges (Euphorbia spp.), making E. semiperfoliata a unique source of macrocyclic diterpenoids.