Systematic alkaloid investigations of various cultivated strains (Coker-319, Virginia Delcrest, Kallo, Palmonostor) of Nicotiana tabacum L. (Solanaceae) were carried out with hplc. The presence of 2,4’-dipyridyl and 4,4’-dipyridyl could be presumed in the Palmonostor strain due to the retention data and uv spectra obtained by diode array detection. The other three dipyridyl isomers have been known for a long time (1,2). In 1980, Saint-Jalm and Moree-Testa (3) identified 2,4’-dipyridyl in tobacco smoke with a gems method. Now 2,4’-dipyridyl and 4,4’-dipyridyl are reported for the first time being present in N. tabacum. © 1986, American Chemical Society. All rights reserved.