1-imidazolylalkyl-substituted or 5-thiazolylalkyl-substituted tetrahydronaphthalenecarboxylic acid and indancarboxylic acid derivatives were prepared and tested for the inhibitory activities of thromboxaneA2 (TXA2) production in vitro and ex vivo. Most of the compounds showed potent TXA2 synthetase inhibitory activities in vitro and had long duration of inhibition of TXA2 production in rats when orally