1. The dry rhizomes of Nuphar luteum L. have yielded three sulfur-containing alkaloids: two - thiobinupharidine and neothiobinupharidine - were known substances, the third with composition C30H42O4N2S being new and having been given the name of nuphleine. 2. A possible structure has been proposed for nuphleine. © 1968 The Faraday Press, Inc.