Non-steroidal anti-inflammatory drugs (NSAIDs) such as piroxicam and mefenamic acid are commonly prescribed to treat inflammation, pain and fever. Similarly acetylsalicylic acid is used to prevent strokes and heart attacks. A rapid and selective method was developed for the simultaneous assay of three NSAIDs and salicylic acid via HPLC with fluorescence detection. The separation was performed using a “dual-mode” gradient (acetonitrile–0.1% aqueous orthophosphoric acid) and the analysis was completed within 7 min using an ACE ® column C18, 5 μm, 150 mm × 4.6 mm. Naproxen was used as internal standard. The proposed method is simple, selective as well as with a good sensitivity reaching LOD lower than 2 pmol (0.05 μM) and was applied for quantitative analysis in pharmaceuticals and in human serum samples. The mean recovery was more than 95% and the within-day and between-days precisions were found to be satisfactory having RSD within the acceptable limits (<10%).