A bioanalytical method for determination of eflomithine (DEMO) in 1000 p,L human plasma has been developed and validated. DFMO and the internal standard (IS) were analysed by liquid chromatography with evaporative light-scattering detection (ELSD). Separation was performed on a Chirobiotic TAG (250 mm x 4.6 mm) column with ethanol (99.5%):0.01 mol/L acetic acid-triethylamine buffer at the rate of 25:75% (v/v) with flow rate of 1.0 mL/min. For D-DFMO in plasma the inter-assay precision was 6.5% at 75 p,mol/L, 6.6% at 375 mu mol/L and 5.8% at 750 mu mol/L. For L-DFMO in plasma the inter-assay precision was 10.4% at 75 mu mol/L, 6.5% at 375 mu mol/L and 5.0% at 750 lumol/L. The lower limit of quantification (LLOQ) was determined to 25 mu mol/L where the precision was 4.3% and 5.7%, respectively.