The systematic review of prevalence and incidence data is important in the description of the geographical distribution of a variable, variation between subgroups (such as gender) and informing health care planning and resource allocation. Pooling of such data is necessary to monitor trends in disease burden and emergence and to contribute to the design of further etiological studies. Systematic reviews are of particular relevance where individual studies are limited by small sample sizes. The systematic review of studies to answer questions of prevalence and incidence data still follow the same basic principles of systematic review of other types of data. A protocol must be written for the conduct of the systematic review, comprehensive searching must be performed and critical appraisal of retrieved studies must be carried out.