Capillary zone electrophoresis (CZE) coupled with tris(2,2'-bipyridyl) ruthenium(II)-based end-column electrogenerated chemiluminescence(ECL) has been utilized to detect bisoprolol in drugs and tablets after its separation from metoprolol. Tetrahydrofuran was used as an additive in the running buffer to obtain the absolute ECL peak of bisoprolol. Bisoprolol reacts as a co-reactant in tris(2,2'-bipyridyl) ruthenium(II) ECL system. Under the optimized experimental conditions, bisoprolol was separated successfully and efficiently from metoprolol and other co-existed materials in tablets and urine samples. The ECL intensity of tris(2,2'-bipyridyl) ruthenium(II)-bisoprolol-based system is linear with the concentration of bisoprolol from 1.5 mu M to 0.3 mu M with a detection limit of 0.3 mu M. Relative standard derivations of the ECL intensity are 2.58% for the detection of 15 mu M bisoprolol. This method is a simple, rapid, selective. and sensitive. It was applied successfully for the monitoring of bisoprolol in market available tablets and human urine samples. (C) 2008 Elsevier Ltd. All rights reserved.