The isolation of mahanimbine, girinimbine and two new carbazole alkaloids isomahanimbine and koenimbidine from the leaves and roots of Murraya koenigii Spreng. is reported. Spectroscopic and degradative evidence has been presented supporting structures for girinimbine (3), mahanimbine (4), isomahanimbine (13), koenimbidine (17) and murrayacine (12). © 1970.