The first dispersive liquid liquid microextraction scheme followed by liquid chromatography-post column derivatization for the determination of the antiviral drug rimantadine in urine samples is demonstrated. The effect of the type and volume of organic extraction solvent, type and volume of disperser solvent, sample pH, ionic strength, extraction time, and centrifugation speed on the extraction efficiency were studied. Rimantadine and the internal standard (amantadine) were chromatographed using a reversed phase monolithic stationary phase with a mixture of equal volumes of methanol and phosphate buffer (pH = 3) as mobile phase. On-line postcolumn derivatization of the analyte was performed using a "two-stream" manifold with o-phthalaldehyde and N-acetyl-cysteine at alkaline medium. Under the optimized extraction conditions, the enrichment factor of rimantadine was 58. The linear range was 5-100 µg/L with correlation coefficient r of 0.9984 while the limit of detection achieved was 0.5 µg/L. The within-day and between-day precision for the tested concentration levels were less than 14.3% and the mean recoveries obtained from the spiked samples were ranged between 87.5 and 113.9%. The main advantages of the proposed method are the simplicity of operation, rapidity, low cost, and low limit of detection of the analyte. K E Y W O R D S rimantadine, dispersive liquid liquid microextraction, liquid chromatography, post-column derivatization, urine J Sep Sci 2020;43:631-638.2. The proposed DLLME scheme offers significant advantages including simplicity, low operation cost employing typical laboratory equipment, high extraction efficiency, and enrichment at a relative short extraction time.3. The sensitivity is almost 10-times higher compared to analogous methods using conventional SPE as sample treatment.4. Besides sensitivity, the combination of the DLLME with on-line PCD offers high selectivity, a feature that is always important in bioanalytical applications.