A gradient reversed-phase high performance liquid chromatographic method was developed for determining NSC 737664 (2-[(2R)-2-methylpyrrolidin-2-yl]-1H-benzimidazole-4-carboxamide; ABT-888) in human plasma and urine. Chromatographic separation used a mobile phase composed of 0.1% formic acid in water and 0.1% formic acid in acetonitrile, and a C18 column (150 mm × 4.6 mm, 5µ). Quantitation was performed using UV detection at 300 nm. Chromatographic peak identity was confirmed using positive-ion electrospray ionization mass spectrometry. The method was shown to be specific, accurate and reproducible, and thereby appropriate for monitoring plasma and urine levels of the agent in support of a phase 0 clinical study.