The objective of the current study was to evaluate the rate and extent of absorption of a test formulation (sitagliptin hydrochloride) and a reference formulation (sitagliptin phosphate). An open-label, randomized, single-dose, single-center, 2-sequence, 2-period, and cross-over phase 1 study was implemented to assess the pharmacokinetic bioequivalence of the test and reference formulations containing a single dose of sitagliptin 100 mg in 32 healthy volunteers under fasting conditions. The differences between the test and reference formulations in terms of the area under the curve from dosing to the time of the last measured concentration (AUC<sub>last</sub>) and the maximum concentration (C<sub>max</sub>) were found to be not significant. The 90% confidence intervals of sitagliptin Ln-transformed AUC<sub>last</sub> and C<sub>max</sub> were within the pharmacokinetic bioequivalence acceptance range of 80%-125%. The test formulation with sitagliptin hydrochloride was bioequivalent to the reference formulation with sitagliptin phosphate in healthy male volunteers under fasting conditions.