Two cytotoxic triterpenes have been isolated from Euphorbia pulcherrima. Their structures and stereochemistry have been established from NMR, IR, and EI-mass spectroscopy. The compounds were identified as 9,19-cycloart-23-ene-3 beta,25-diol and, 9,19-cycloart-25-ene-3 beta,24-diol. Cytotoxicity evaluation was performed using Ehrlich ascites tumor cells. While cycloartenol induced no cytotoxic activity against Ehrlich ascites tumor cells, both isolated triterpenes exhibited cell inactivating effects. The IC50 is approximately 7.5 microM, while the IC90 is approximately 13.5 microM for 9,19-cycloart-25-ene-3 beta,24-diol. The 3 beta,25-diol compound is 50% less active.