A high performance liquid chromatography/ultraviolet method developed for the simple and direct determination of β-hydroxy-β-methylbutyrate (HMB) in liquid nutritional products and dietary supplements is described. Method suitability was defined by experimental assessments of linearity (r 2 > 0.9999), precision (day-to-day RSD <1.5%), accuracy (spike recoveries = 98.1–102.4%, n = 28), selectivity (peak purity average = 99.8 ± 0.8%, n = 10; absence of interference verified by placebo analysis), and quantitation limit (90 mg/kg or 0.8 mM). The method provides for a simple, accurate, and precise quantification of HMB, when present at millimolar concentrations in liquid nutritional products and dietary supplements.