The alkaloids dehydrocorydalmine and oxyberberine isolated from Argemone mexicana were assessed against spore germination of some fungi, e.g., Alternaria cajani, Bipolaris sp., Helminthosporium sp., Fusarium udum and Curvularia sp. While dehydrocorydalmine inhibited 100% spore germination of the fungi Helminthosporium sp. and Curvularia sp. at 5 000 ppm, oxyberberine showed similar activity against spore germination of Bipolaris sp. and Curvularia sp. All the five fungi were significantly inhibited at 1 000 to 5 000 ppm concentrations.