A method for the determination of sulfadoxine and sulfamethoxazole in capillary blood on sampling paper has been developed and validated. The method is straightforward with minimal sample preparation, and is suitable for rural settings. Separation of sulfadoxine, sulfamethoxazole and internal standard was performed using a Purospher STAR RP-18 endcapped LC column (150 x 4.6 mm) with a mobile phase consisting of acetonitrile: sodium acetate buffer pH 5.2, 1=0.1 (1:2, v/v). For sulfadoxine, the within-day precision was 5.3% at 15 mu mol/l and 3.7% at 600 mu mol/l, while for sulfamethoxazole it was 5.7% at 15 mu mol/l and 3.8% at 600 mu mol/l. The tower limit of quantification was determined to 5 mu mol/l and precision was 5.5% and 5.0% for sulfadoxine and sulfamethoxazole, respectively.