In addition to the previously reported alkaloids from Mitragyna speciosa a number of additional oxindole alkaloids were isolated, three of which are new. These have been named mitrafoline, isomitrafkline and isospeciofoline. Mitragynine oxindoles A and B were found for the first time in plant material while corynoxeine and the corynoxines were found for the first time in the genus Mitragyna. Examination of thirteen monthly samples of leaves showed that mitragynine and paynantheine remained the dominant indole alkaloids of the mature plant throughout the entire period of collection.