A high performance liquid chromatographic procedure is presented for the determination of nabumetone in pharmaceutical tablets and in plasma. An aliquot of the sample is dissolved in 50% acetonitrile (ACN) containing 4-methoxyacetophenone as an internal standard and chromatographed on a Supelcosil LC-8 (5μ) (150 mm × 4.6 mm i.d.) column. The mobile phase was a mixture of acetonitrile (500 mL), triethylamine (1.5 mL) and glacial acetic acid (8 mL) diluted to 1000 mL, with distilled deionized water. The detection was carried at 270 nm. The method was tested for linearity, recovery and specificity.