The aim was to assess the effects of resistance training and vitamin D supplementation on physical performance of healthy elderly subjects. Ninety-six subjects, aged 70 years or more with 25 OH vitamin D levels of 16 ng/ml or less, were randomized to a resistance training or control group. Trained and control groups were further randomized to receive in a double blind fashion, vitamin D 400 IU plus 800 mg of calcium per day or calcium alone. Subjects were followed for nine months. Serum 25 OH vitamin D increased from 12.4+/-2.2 to 25.8+/-6.5 ng/ml among subjects supplemented with vitamin D. Trained subjects had significant improvements in quadriceps muscle strength, the short physical performance test and timed up and go. The latter improved more in trained subjects supplemented with vitamin D. At the end of the follow up, gait speed was higher among subjects supplemented with vitamin (whether trained or not) than in non-supplemented subjects (838+/-147 and 768+/-127 m/12 min, respectively, p=0.02). Romberg ratio was lower among supplemented controls than non-supplemented trained subjects (128+/-40% and 144+/-37%, respectively, p=0.05). In conclusion, vitamin D supplementation improved gait speed and body sway, and training improved muscle strength.