Vitamin D deficiency is common in the elderly, especially in countries where effective sunlight or exposure to sunlight is limited. Two regimes for vitamin D supplementation--low-dose daily oral administration and intermittent high-dose administration--were examined with regard to safety and effectiveness. Eleven papers reporting studies in 449 elderly subjects were reviewed. On low-dose continuous supplementation mean concentration of 25 hydroxyvitamin D (25(OH)D) ranged from 57 to 105 nmol/L compared to 55 to 87 nmol/L following high-dose supplementation. These mean values fall within the physiological range for young adults. Hypercalcemia occurred in only 3 subjects and was associated with a predisposing cause in 2 of 3 subjects. We suggest that low dose continuous supplementation (10 to 20 micrograms daily) is the regime of choice but high-dose intermittent supplementation (2.5 mg six monthly) may be suitable where compliance is poor.