<jats:p>In addition to the alkaloids previously found in the aerial part of <jats:italic>P. atlanticum</jats:italic> BALL, <jats:italic>viz.</jats:italic> protopine, rhoeadine (predominant constituents), rhoeagenine, stylopine, cryptopine, sanguinarine, magnoflorine and papaverrubines A, B, E and D, we have now isolated the tertiary bases isothebaine, scoulerine, corytuberine and a new quaternary alkaloid 13β-hydroxy-N-methylstylopinium hydroxide (<jats:italic>I</jats:italic>). The presence of papaverrubine B and muramine was also detected (TLC). The contents of the bases in the roots of <jats:italic>P. atlanticum</jats:italic> were found similar to those in the aerial part. Magnoflorine was isolated from the roots in a considerable yield. The dominant alkaloids isolated from <jats:italic>P. glaucum</jats:italic> BOISS. <jats:italic>et</jats:italic> HAUSKN. were glaudine and glaucamine; they were accompanied by protopine, papaverrubine B and traces of sanguinarine, coptisine and papaverrubine C. Magnoflorine and corytuberine have been isolated from this species for the first time and the presence of allocryptopine, cryptopine, corydine, isocorydine and papaverrubines D and H has been demonstrated.