Abstract This study compares the bioequivalence of three ascorbic acid formulations (test: Celong 500 mg prolonged release tablets from Whitehall; standard: Cewin 500 mg prolonged release tablets from Winthrop and Redoxon oral effervescent 1000 mg tablets from Roche) in seventeen healthy male volunteers. A single oral dose of 1000 mg of the appropriate formulation was administered according to a randomized cross-over way with a two week washout interval between periods. Plasma samples for HPLC determination of ascorbic acid were obtained before and at set intervals up to 48h after the administration of each formulation. From the plasma concentration vs. time curves obtained for each formulation, the following parameters were obtained: areas under the curves (AUC) from 0 to 12 h and from 0 to 48 h, maximum achieved concentration (Cmax) and the time at which it occurred (Tmax). Parametric and non-parametric analysis of individual AUC and Cmax ratios and Tmax differences among formulations showed no statistical significance, despite their different patterns of drug release. Based on the above results and in accordance with the European Union and the US Food and Drug Administration, Celong was found to be bioequivalent to both Cewin and Redoxon, and also Cewin was bioequivalent to Redoxon with regard to both the extent and rate of absorption.