Ascorbic acid may be determined spectrophotometrically at 360 nm based on reduction of vanadotungstophosphoric acid using flow-injection analysis. The carrier stream was distilled water and the reagent streams were buffer solution (pH 3.0), 1.735 x 10(-3) M dodecatungstophosphoric acid and 1.735 x 10(-3) M sodium vanadate. The injection rate was 80 h-1. The calibration graph was linear up to 80-mu-g ml-1 ascorbic acid and the relative standard deviation for the determination of 20-mu-g ml-1 ascorbic acid was 1.5% (n = 10). The detection limit was 1.0-mu-g ml-1 ascorbic acid, based on an injection volume of 250-mu-l. The system was applied to the determination of ascorbic acid in vitamin C tablets.