Background/Aims. Vitamin D3 is liposoluble, so dietary fat could increase its oral absorption. Our aim was to compare serum 25-hydroxyvitamin D [25(OH)D] after the oral intake of cholecalciferol with a high- or low-fat meal. Methods. In a single-blind, parallel clinical trial, 32 healthy physicians were divided into two groups. In the same day, they ingested 50,000 IU (1.25 mg) of vitamin D3 with food: group 1 (G1): lipids: 25.6 g and group 2 (G2) lipids: 1.7 g. Serum 25(OH)D (0, 7, and 14 days), and parathyroid hormone (PTH), and calcium (0 and 14 days) were measured. Results. Baseline mean serum 25(OH)D levels were 42.7 ± 19.0 nmol/L in G1 and 36.4 ± 19.0 nmol/L in G2 (P = 0.38). After cholecalciferol, mean serum 25(OH)D was higher in G1 (P < 0.001): 7 days: G1 = 46.2 (38.4–53.9) nmol/L and G2 = 33.7 (25.4–40.1) nmol/L; 14 days: G1 = 53.7 (45.2–62.1) nmol/L and G2 = 33.7 (25.2–42.2) nmol/L. Serum PTH and 25(OH)D were negatively correlated before and after the intake of vitamin D3, respectively, r = −0.42 (P = 0.02) and r = −0.52 (P = 0.003). Conclusions. A high-fat meal increased the absorption of vitamin D3, as measured by serum 25(OH)D.