The tetrahydropahnatine alkaloid was assayed against spore germination of some saprophytic and pathogenic fungi e.g., Alternaria solani, A. brassicicola, A. brassicae, A. alternata, Erysiphe pisi, Curvularia lunata, C. pallescens, C. maculans, Curvularia species, Colletotrichum species, C. musae, Helminthosporium echinoclova, H. pennisetti, H. spiciferum, and Heterosporium sp. It inhibite spore germination of all the fungi tested. Colletotrichum spp. Curvularia lunata, Helminthosporium spiciferum and Heterosporium sp. were most sensitive as complete inhibition of spore germination was observed at very low concentration(200 ppm).