Optimal Vitamin D dosing to obtain adequate serum concentrations of 25-hydroxyvitamin D (25OHD) is controversial. The optimal dose and dosing interval is unknown, and the tendency over the last few years is to give higher, less frequent doses. Disease-specific dosing is of interest, and there may be optimal serum concentration targets based on disease process. The best evidence so far is for optimal bone health, where most experts agree that 25OHD serum concentration should be above 30 ng/ml.