A crystalline polymorph of a bisulfate salt of a thrombin receptor antagonist compound, which exhibits a powder x-ray diffraction profile substantially the same as that shown in FIG. 1, or which exhibits a differential scanning calorimtery profile substantially the same as that shown in FIG. 3, and is represented by the formula for Compound 2: ##STR00001## and processes for preparing Compound 2 are disclosed.Pharmaceutical compositions comprising the polymorph of the bisulfate salt and at least one excipient or carrier, and methods of using the polymorph of Compound 2 to treat a variety of physiological disorders, such as thrombosis, are also disclosed.