Omeprazole belongs to a class of drugs known as Proton Pump Inhibitors (PPI’s). It is used in the treatment of conditions relating to overactive stomach acid such as gastroesophageal reflux disease, peptic ulcers and Zollinger-Ellison syndrome. The World Health Organization regards omeprazole among its ‘List of Essential Medicines’ which outlines the most effective and safest medicines required by a countries healthcare system to meet its needs. Omeprazole is a very commercially important drug, being ranked as the 7th most prescribed drug in the USA in 2017 with over 58 million prescriptions. This application brief describes the use of a Quasar C8 column for the analysis of omeprazole in accordance with the United States Pharmacopoeia (USP) monograph.