Molecular mechanics and conformation search methods were carried oyt to investigate the relationship between conformations and thromboxane synthetase ingibitory activities of om ega-pyridylalkenoic acids. The initial geometries of ${omega}$-pyridylalkenoic acids and heme part of cytochrome P-450 were obtained from MM+ geometry optimization. The bond lenths and angles were not varied by step during the conformation searching. Stable conformers of some ${omega}$-pyridylalkenoic acids were obtained by comformational search method. The distances were 8.5~10.8 ${AA}$- between N atom at 3-position of pyridine ring and C atom at carboxylic group of stable ${omega}$-pyridylalkenoic acids. The conformations of ${omega}$-pyridylalkenoic acids and heme part complex were determined by same method. In theses structures, benzene ring and ethylene group in ${omega}$-pyridylalkenoic acids are making the structure more rigid and increase inhbitory activity. The electron donating groups in C atom shich is connected to pyridine ring also increase activity.