A novel flow injection procedure was developed for the determination of tannic acid in industrial wastewaters based on the enhancement by tannic acid of the chemiluminescence from luminol-K3Fe(CN)6-OH- system. The method has the merits of higher sensitivity, higher selectivity, wider linear range, simpler instrumentation. It is applicable for the determination of tannic acid in the range of 3.0 x 10(-10)-1.0 x 10(-7) mol/L with a detection limit of 1.0 x 10(-10) mol/L. The relative standard deviation is 2.7% for the determination of 1.0 x 10(-8) mol/L tannic acid (n = 11). The method has been successfully used to determine tannic acid at trace level in industrial wastewaters from brewery and tannery.