Aim and Background: A botanical study is conducted to provide a standard diagnostic tool. In order to improve the quality assurance of the secondary tuberized roots of Harpagophytum procumbens, derived extract and phytomedicine, a simple, rapid, and accurate high-performance liquid chromatography (HPLC) method was developed to assess the harpagoside. Material and Mehods: This HPLC assay was performed on a reversedphase C18 column with methanol and water (50/50-V/V) as the mobile phase with a flow rate of 1.5 mL/min and using a monitoring wavelength at 278 nm. Results and Conclusion: This method was successfully applied to quantify these bioactive iridoid in an aqueous extract of H. procumbens and in its related phytomedicine "harpagophyton." The result demonstrated that the quantification of harpagoside, indicating that the quality control of the bioactive ingredient in H. procumbens, derived extract and phytomedicine, is critical to ensure its clinical benefits.