Three macrocyclic pyrrolizidine alkaloids have been isolated from the flowers of Crotalaria rosenii. Two of them , madurensine 1 and 7-acetylmadurensine 2 are rare but known alkaloids for which full spectroscopic data have been generated and some erroneous 13CNMR data in the literature corrected. Crotaflorine 3, an alkaloid previously given a “probable” structure has been subjected to detailed spectroscopic