Abstract: An injection sample containing procaine hydrochloride (I) and p-aminobenzoic acid (Ⅱ) was diluted with pH 10 buffer soln. and determined with 751G spectrophotometer at 287,284.5nm in dual wavelength spectrophotometry or at 264,287,315 nm in three wavelength spectrophotometry for the determination of Ⅰ. Absorbance showed a linear dependence on the concentration of I in the range of 3—11 μg/ml. The mean recoveries of two methods were found to be 99.68±0.35% and 99.51％±0.46％, respectively. The results obtained from four batches of samples showed no significant difference between the two methods at 95% confidence level.