Papaver lateritium Koch (section Pilosa), cited by Cullen in the Flora of Turkey, is endemic to Turkey and grows at an altitude of 1200—3000m in the North-east Anatolia (1). This species is very close to P. oreophilum F. J. Rupr. and P. monanthum Trautv. which are both Caucasian species. These two species cited in the Flora URSS 1937 are also considered as varieties of P. latentium (2). Previous investigations on the alkaloids of this species revealed the existence of latericine (1) (benzyltetrahydroisoquinoline), protopine (2) (protopine), rhoeadine (3), rhoeagenine (4) and papaverrubine A, B, D, E (5, 6, 7, 8) (rhoeadine (3—7). In the present work the major alkaloid of P. lateritium Koch collected in Rize was identified as rhoeadine [(+)-rhoeagenine] type. Secoberbine [(+)-macrantaline (9)], retroprotoberberine [(—)-mecambridine (10)], tetrahydroprotoberberine [(—)-a-N-methyltetrahydropalmatine (11)], protopine [cryptopine (12), protopine] types were isolated as minor alkaloids. This is the first report about the isolation of compounds 9—12 from P. lateritium. The presence of 9 and 11 has been shown for the first time in the section Pilosa. The existence of 2 and 3 as major alkaloids from the same species collected from the same location in September was shown by HPLC in the previous work (7). The variation in the major alkaloid content in the species may probably be due to the different collection time and the similarities between the R1 values of 3 and 4 on HPLC. The cytotoxicity assay using Artemia sauna (brine shrimp) has also been carried out on the fraction with tertiary, and that with quaternary alkaloids as well as on 4. The quaternary alkaloid fraction showed the highest lethality to brine shrimp larvae (Table 1). Previous investigation on the cytotoxicity of Papaver alkaloids using the same method revealed 10 as the most cytotoxic compound (14). Therefore 10 in the tertiary alkaloid fraction may have an effect on lethality.