Abstract: Procainamide(I) and N-acetylprocainamide(II) were determined by a commercial EMIT method (Syva Co.), modified to permit automated analysis of ~100 samples per day in a working range of 0.1 to 2.0 µg mL-1. A Gilford 203S continuous-flow system was used, with a Beckman Model DU spectrophotometer. The calibration graph was prepared by using I or II concentration. of 0, 0.1, 0.2, 1.6, 1.0 and 2.0 µg mL-1 and had a standard deviation of 5%. In a study in which 0.1 to 10 µg mL-1 of I and II were determined in duplicate, average recoveries, calculated from data obtained on two separate days were 99.5% (coefficient of variation 2.2%) and 100.4% (coefficient of variation 3.0%) for I and II, respectively. At extreme ratios of I to II the accuracy of determining the lower concentration. component became unsatisfactory.