Recently, it was reported that electron diffraction can be used to determine polymorphs in pharmaceutical industry [1]. The term polymorph refers to substances that have the same chemical formula but different crystal structures. Polymorphism has played an important role in drug development, production and litigation [2]. Synthesized and crystallized under different conditions, polymorphs may have different physical and chemical properties as well as bioavailabilities. The conventional techniques used to identify polymorphs .sometimes fail to differentiate definitively between two structurally similar polymorphs such as roxifiban, a very promising cardiovascular drug discovered recently at DuPont Pharmaceuticals [3,4]. Bulk and tapped densities of Form I and II, for example, were found to vary from 0.23 and 0.37 g/ml for Form I to 0.07 and 0.19 g/ml for Form II, respectively. These differences were of some concern given the low drug load in the solid dosage form. Unit cell parameters and atomic coordinates of crystalline polymorphs can routinely be determined by single-crystal xray diffraction techniques if suitably large crystals are available. However, many organic compounds tend to grow needle and plate-like crystals that never achieve a large enough volume for single-crystal studies. Such was the case with forms I and II of roxifiban.