The bis(oxazolyl and/or thiazolyl)hydrazines were prepared, and their anti‐allergic activity was studied. All the compounds displayed variable extent of anti‐allergic activity on immunoglobulin E/silver‐stimulated RBL‐2H3 cells at 50 and 100 μM concentrations. The unsubstituted and chlorosubstituted compounds showed higher activity than those having methyl substituent. Compounds 9c and 10c do not cause