Vitamin D sufficiency has been associated with improved health outcomes but cost benefit analyses of published data adopt a number of assumptions. Firstly, definitions of vitamin D deficiency vary Secondly, available methods used for the analysis of 25-hydroxyvitamin D (25OHD) have significant limitations which could affect the adoption of specific target thresholds for treatment. Thirdly, although a variety of diseases are associated with vitamin D deficiency, randomised clinical trial data demonstrating the benefit of vitamin D supplementation only exist for the prevention of falls or fractures. This review will summarise the current evidence regarding an appropriate target threshold of 25OHD and review proposed therapeutic target thresholds of treatment. The limitations of current methods will be reviewed and objective data relating to the costs of diagnosis, the costs of treatment, and the level of evidence that screening could lessen disease burden in the community, will be provided. Finally, information needed by governments and health organisations to help justify population screening and what strategies could be adopted to make screening more cost-effective will be explored.