The present application discloses crystals of2-acetoxy-5-(.alpha.-cyclopropylcarbonyl-2-fluorobenzyl)-4,5,6,7-tetrahydrothieno[3,2-c]pyridine hydrobromate, crystal compositions and pharmaceutical compositionscomprising them and their use. The crystals of prasugrel hydrobromate of thepresentapplication possess excellent stability and solubility.