The structure activity relationship of flavonoids for anti-allergic actions was studied by determining the $IC_{50}$ values for the degranulation. The hexosaminidase release from RBL-2H3 cells (degranulation marker) was employed as an estimate for the anti-allergic actions. Among 22 flavonoid compounds tested, luteolin, apigenin, diosmetin, fisetin, and quercetin were found to be most active with $IC_{50}$ values less than 10 $mu extrm{M}$.