Diterpene esters of the phorbol and ingenol types are known to be highly active tumor promoting agents that typically occur in members of the Euphorbiaceae. In the present work, Euphorbia leuconeura, a rare indoor plant, is analyzed for its tumor promoting potential. Latex as well as total leaf extracts exhibited Epstein-Barr-virus (EBV) inducing activity comparable to 12-O-tetradecanoyl-phorbol-13-O-acetate, a well known tumor promoter. The activity of individual fractions correlated with their ingenol ester content. Three ingenol esters with EBV inducing activity could be isolated and identified. They belong to the milliamine type of diterpene esters that contain aromatic peptidyl groups. Two of them (milliamines L and M) are already known from E. milii. The third compound is identified as an isomer of milliamine F with a novel 3,20-diester arrangement. The data show a close relationship between E. leuconeura and the more popular indoor plant E. milii whose latex is also used as a powerful molluscicide.