Reactions between cinnamoyl(2-hydroxybenzoyl)methanes and hydrazine hydrate in acetic acid gave 3-(2-hydroxyphenyl)-5-styrylpyrazoles, while the corresponding reactions with phenylhydrazine yielded 5-(2-hydroxyphenyl)-1-phenyl-3-styrylpyrazoles as the major products and 3-(2-hydroxyphenyl)-1-phenyl-5-styrylpyrazoles as by-products. The reaction mechanism of this transformation is discussed. The first