Two (E)-pyridinyl-substituted flavanone derivatives were synthesized and UV irradiation of these compounds afforded a Z-enriched mixture. These products were tested for their ability to inhibit the cytochrome P450 aromatase. It was observed that the introduction of a pyridinylmethylene group at carbon 3 on flavanone nucleus led to a significant increase of aromatase inhibitory effect. Moreover, configuration had a substantial influence on the aromatase inhibitory activity since (E)-isomers were found to be more active than (Z)-isomers.