Alkaloids neothiobinupharidine and thionuphlutine-A were isolated from rhizomes of Nuphar luteum obtained from Poland. These two alkaloids were not detected in the two North American Nuphar examined. However a bishemiaminal form of thionuphlutine-A has been isolated from North American Nuphar. Thionuphlutine-A is identical with the previously reported thiobinupharidine. © 1972.