Spectrophotometric determination of procaine hydrochloride is described. The procaine hydrochloride reacts with p-dimethylaminobenzalhyde in glacial acetic acid to form an Schiff base which is a yellow compound, and its maximum absorption wavelength is at 455nm, epsilon(455)=3.46x10(4). The absorbance for procaine hydrochloride from 0.2 to 15 mug ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C=5.866A-0.02, with a linear regression correlative coefficient is 0.9994 and relative standard deviation (RSD) of 1.7%; the detection limit is 0.1 mug ml(-1); recovery is from 92.0 to 110.0%. Effects of reaction medium, temperature, gentamycin, beneylpenicillin, kanamycin, streptomycin, foreign ions, and stand for time on the determination of procaine hydrochloride have been examined. The results obtained by this method agreed with those by the official method (dead-stop titration). This method is rapid and simple, and can be used for the determination of procaine hydrochloride in injection solution of procaine hydrochloride.