The basic fraction of spearmint Midwest Scotch oil (spearmint MWS, Mentha gentilis f. cardiaca) was analyzed by fused silica capillary gas chromatography and mass spectrometric techniques. A total of 38 nitrogen-containing components including 11 new pyridine derivatives, 2-isopropyl-4-methylpyridine, 4-isopropenyl-2-methylpyridine, 2-ethyl-4-isopropenylpyridine, 2-acetyl-4-isopropylpyridine, 2,4 diisopropenylpyridine, 2-acetyl-4-isopropenylpyridine, 4-acetyl-2-isopropenylpyridine, 5- [ (Z)-l-buten-1-yl]-2-propylpyridine, 5-(E)-l-buten-1-yl]-2-propylpyridine, 3- [(Z)-l-buten-1-yl]-4-propylpyridine, and 3-[(E)-l-buten-1-yl]-4-propylpyridine, were identified by comparison of their spectroscopic data with those of synthetic samples. Among them, 2-acetyl-4-isopropenylpyridine is a major component and has a powerful grassy-sweet and minty odor. The typical basic components in spearmint oil were compared with those of peppermint oil. Odor profiles of 15 pyridine derivatives were also described.