As a result of feeding young plants of Mitragyna parvifolia (Roxb.) Korth with 14C-akuammigine an active alkaloidal spot was detected on a thin layer chromatogram which could not easily be identified (Shellard and Houghton 1973). However, a similar alkaloidal substance had been detected earlier in the alkaloidal extract from leaves of Mitragyna parvifolia obtained from Sri Lanka (Ceylon) but never isolated (Shellard and Houghton 1971). Because of its possible significance in the biogenesis or metabolism of indole alkaloids in Mitragyna species it was decided to isolate the substance from the Singhalese leaves. In actual fact the substance was found to consist of two isomers, identified as corynantheidol (allo) and dihydrocorynantheol (normal).