An assay for nicotinic acid in plasma samples has been developed using ion exchange solid phase extraction in 96-well format followed by mixed-mode ion exchange/reversed-phase liquid chromatography with positive ion tandem mass spectrometry detection. The assay avoids the need for time-consuming derivatisation procedures or involatile ion-pair chromatography reagents. The assay is linear over the wide range 0.05-20 microg/mL, based on a 100 microL sample (correlation coefficient>0.99). The assay is accurate and precise (bias and coefficient of variation<18%) over this calibration range.