Nearly 60 species from the generaEuphorbiaL. andElaeophorbiaStapf were investigated for diterpenes of the classes tiglianes, ingenanes and ortho‐esters. The diterpenes were isolated as their acetates by a micro‐technique from latex or fresh herb material collected from several countries around the world. Authentication of the diterpenes was by chromatographic means using spectroscopic methods as back‐up data. These compounds were absent from only 9% of the species examined. The most commonly occurring diterpene was ingenol, followed closely by 12‐Deoxy phorbol. The ingenane derivative 5‐Deoxy‐ingenol was always detected as a minor companion to ingenol from species of the sectionTithymalus.Species of the sectionEuphorbiumcontained mainly the diterpene ingenol although both tigliane and ortho‐ester diterpenes were also present in some species. Species from the sectionsAnisophylhtmandPoinsettiadid not contain diterpenes of the type in question, whilst species from the genusElaeophorbiayielded ingenol. These results provide additional chemical evidence concerning recent suggestions on the subgeneric and generic status ofAnisophyllum, Poinsettia, Tithymalusan