Fenfluramine-imprinted polymer was prepared by self assembly with acrylic amide as functional monomer and ethylene glycol dimethacrylate as crosslinker. The binding characteristics of the imprinted polymer to fenfluramine were evaluated by equilibrium binding experiments and the morphology was studied by SEM. Taking the imprinted polymer as recognition material, using the new 3-p-nitrylphenyl-5-(4'-methyl-2'-sulfonophenylazo)rhodanine (M4NRASP) synthesized by the authors as chemiluminescence reagent, a new highly selective flow injection chemiluminescence sensor for trace fenfluramine with good sensitivity was established which utilized the chemiluminescence reaction between fenfluramine, M4NRASP, and potassium permanganate in hydrochloric acid. The traditional flow-through cell was replaced with a polymethyl methacrylate module, with Y-shaped flow path, through which the above three reactants were injected simultaneously. Under optimum conditions the relative chemiluminescence intensity shows a linear relationship with the concentration of fenfluramine over the range of 5 x 10(-7) to 8 x 10(-6) g/mL with a lower detection limit of 3.4 x 10(-8) g/mL. The relative standard deviation for the determination of 1.0 x 10(-6) g/mL fenfluramine solution was 2.4% (n = 11). This proposed sensor could be satisfactorily applied to the determination of fenfluramine in weight-reducing capsules.