<p>The ¹⁴N nuclear quadrupole resonance (NQR) spectrum of albendazole has been recorded using cross relaxation double resonance. Albendazole is a broad spectrum anthelmintic benzimidazole with methyl carbamate ester and propyl sulfanyl substituents which is mainly used in the treatment of parenchymal neurocysticercosis and other helminth (parasitic worm) infections. Benzimidazoles are heterocyclic aromatic organic compounds comprising fused rings of benzene and imidazole which have two distinct nitrogen atoms. Albendazole has two stable polymorphs. Form I has three distinct nitrogen atoms. Form II is expected to have two distinct nitrogen atoms since the nitrogen atoms on the bicyclic benzimidazole ring are equivalent, however, the results indicate that all three nitrogen atoms are unique. Ab initio calculations have been done to support the assignment of the ¹⁴N NQR experimental frequencies, quadrupole coupling constants, and asymmetry parameters to their respective nitrogen atoms in the albendazole molecule. Significant differences in the expected quadrupole coupling constants, asymmetry parameters and ¹⁴N NQR frequencies for both polymorphs permit the confirmation of the structure and subsequently, authentication of the compound in the solid state. Evidence suggests that proton transfer via an intermolecular hydrogen bond occurs.</p>