The aim of the current study was to examine whether calcium supplementation could prevent bone loss in postmenopausal women or more favourable outcomes could be obtained via the consumption of dairy products fortified with calcium and vitamin D3. For this purpose changes in bone mineral density (BMD) at different skeletal sites, assessed by dual-energy X-ray absorptiometry, as well as in quantitative ultrasound (QUS) parameters of the calcaneus over 12 months were estimated. A population of 101 postmenopausal women (55–65 years old) was randomized into a dairy group (DG: n 39), receiving approximately 1200 mg calcium/d and 7·5 μg vitamin D3/d through fortified dairy products; a calcium-supplemented group (CaG: n 26) provided with a calcium supplement of 600 mg/d; and a control group (CG: n 36). Over the intervention period the DG was found to have more favourable changes in pelvis (P = 0·040), total spine (P < 0·001) and total body BMD (P < 0·001) than the other groups. A significant increase was also observed for DG in lumbar spine BMD (2·0 %; 95 % CI 0·5, 3·5) although it did not differentiate significantly compared to the other groups. No significant differences were observed with respect to the changes in QUS parameters. The current study revealed that recommended intakes of vitamin D3 and calcium via fortified dairy products for 12 months can induce favourable changes in pelvis, total spine and total body BMD in postmenopausal women but not in QUS parameters. No such favourable changes were observed via supplementation of calcium alone.