We conducted an examination of recent studies to determine whether older adults (>or=65 years) need higher levels of supplementary vitamin D than young adults when attempting to replete vitamin D status in deficient subjects, i.e. those with levels of 25-hydroxyvitamin D less than 75 nmol/L. As data on repletion with vitamin D(2) have recently been published, we restricted our discussion to the use of vitamin D(3) from dietary supplements, prescriptions for large oral doses, and bolus dosing or injections. Most published dosing regimens failed to achieve 75 nmol/L in most all subjects, whether young adults (<65 years) or older adults (>or=65 years). Whether as daily or bolus oral supplementation, elderly subjects appeared to need more vitamin D3 compared with younger adults, however, baseline levels, endpoints, study duration, compliance, and other factors were different among studies. To ensure most subjects are replete in vitamin D, a daily dose of more than 50 microg (2000 IU) in younger and 125 microg (5000 IU) is required. Other strategies including bolus and loading doses are described. No study reported adverse effects of using oral intakes about the current upper level of 50 microg (2000 IU).