A novel method based on capillary electrophoresis coupled to laser-induced fluorescence detection (CE-LIF) was developed for the determination of abscisic acid (ABA), which is an essential phytohormone during plant growth and development. ABA was labeled with 8-aminopyrene-1,3,6-trisulfonate via reductive amination in presence of acetic acid and sodium cyanoborohydride. The derivatization yield was maximized by optimizing several derivatization parameters including derivatization reagent concentration, reaction temperature and time. The conjugate was separated and quantitated by CE–LIF. The linearity of ABA was determined in the range from 0.1 to 10µmol l−1 with a correlation of 0.9979. The derivatization limit of detection for ABA was found to be 56 fmol (corresponding to the concentration of 2.8×10−8mol l−1). The detection limit for ABA was 5.5 amol for an injection volume of 5nl. As a preliminary application, the proposed methodwas successfully applied to determining trace amount ofABAin the crude extracts of tobacco without extra purification and enrichment procedure and showed a better selectivity and sensitivity than those conventional methods used in determination of ABA.