Introduction Where no studies relevant to the scientific question being examined meet the pre-specified inclusion criteria, a systematic review becomes an ‘empty review’. As such, no robust evidence based conclusions can be drawn from the findings of these reviews. It may be that such reviews have been undertaken where there is not yet a sufficient body of knowledge to allow for a systematic review being undertaken. In such circumstances, the publication of an empty systematic review may prompt the funding for and development of studies to answer the relevant scientific question. Also, in is much as there is a benefit in knowing what evidence based recommendations can be made in clinical practice, it is also useful to know what commonly used treatments are prescribed based on generally accepted standard practice rather than proven clinical benefit. It may also be, however, that the question being examined is too narrow or too focused, with excessively broad exclusion criteria, to be of relevance in a typical clinical setting. The development of such systematic reviews may be regarded as wasteful in resource limited circumstances.