This study investigated the alkaloids of Glaucium corniculatum from Egypt. Seven alkaloids were identified via UV, MS, ¹H, ¹³C and 2-D NMR: three major ones (protopine, corydine, isocorydine) and four minor ones (corydine N-oxide, isocorydine N-oxide, N-methylcorydine, dihydroprotopine). Five trace alkaloids were also detected, with structures pending further investigation. Alkaloids 4-7 are reported for the first time in Glaucium species. Biosynthetically, the addition of an N-oxide group to corydine and isocorydine is expected in plants containing these alkaloids; low yields of 4 and 5 suggest they are not accumulated but may be transferred into other metabolites or corresponding tertiary bases, while the occurrence of 7 indicates its potential role as an intermediate in the biosynthesis of protopine. The difference in alkaloid profile between the Egyptian sample and other geographical samples may prove the presence of different chemical races within the species, and the appearance of various major alkaloids indicates the Egyptian G. corniculatum is an independent chemoecotype when compared with samples from other countries.