A rapid bioanalytical method has been developed for the determination of pemoline in urine, using 4-methyl-primidone as the internal standard. The analyte was isolated from urine with a C18reverse solid-phase extraction column and analysed by high performance liquid chromatography with a photo diode array detector. The method was linear in the studied range of 0.20 to 1.40 μg/ml urine. For the standard curve a weighted (1/x2) linear regression line (y = - 0.006 + 0.976x) was computed and validated (R2= 0.998). The limit of quantitation was 0.04 μg/ml urine. Recovery studies for the accuracy gave a mean percent recovery of 93.9 and a predicted percent recovery in the range of 91.5 to 96.0. The precision, expressed as coefficient of variation, was in the range of 2.03 to 3.67 μg/ml for the intraday and from 1.96 to 4.35 μg/ml for the inter-day. The ANOVA (analysis of variance) tables were also given to validate the day to day reproducibility. Application of the method to clinical samples was demonstrated.