Abstract This 24-week, double-blind, randomized, multicenter, placebo-controlled, parallel-group study performed in 354 drug-naïve patients with type 2 diabetes (T2DM) assessed efficacy and tolerability of vildagliptin (50 mg qd, 50 mg bid, or 100 mg qd). The primary assessment was change from baseline to endpoint in hemoglobin A1c (A1C), comparing vildagliptin to placebo by ANCOVA. Baseline A1C averaged 8.4% and the between-treatment difference (vildagliptin-placebo) in adjusted mean change (AMΔ) in A1C was −0.5 ± 0.2% ( P = 0.011), −0.7 ± 0.2% ( P < 0.001), and −0.9 ± 0.2% ( P < 0.001) in patients receiving vildagliptin 50 mg qd, 50 mg bid, or 100 mg qd, respectively. Baseline FPG averaged 10.5 mmol/L; the between-treatment difference in AMΔ FPG was −0.6 ± 0.4 mmol/L in patients receiving vildagliptin 50 mg qd and −1.3 ± 0.4 mmol/L ( P = 0.001) in both groups receiving 100 mg daily. Relative to baseline, body weight did not change significantly in any of the three vildagliptin groups and decreased by 1.4 ± 0.4 kg in the placebo group. Adverse events (AEs) occurred with similar frequency in each group: 55.8%, 59.3%, 59.3%, and 57.6% of patients receiving vildagliptin 50 mg qd, 50 mg bid, 100 mg qd, or placebo, respectively, experienced an AE. No confirmed hypoglycemia was reported. Conclusion : Vildagliptin is effective and well-tolerated in drug-naïve patients with T2DM and 100 mg vildagliptin provides similar clinical benefit whether given as single or in divided doses.