Systematic reviews and meta-analysis represent a speciﬁc type of medical research in which an original article is a unit of analysis. These methods of research are essential tools in inte-grating scientiﬁc information, increasing the internal and external validity of the conclu-sions of original articles, and suggesting areas for future research. Meta-analysis is becom-ing popular because it can combine results from similar studies to calculate an overall esti-mate of a treatment effect. They are also necessary for the practice of evidence-based med-icine and the medical decision making. However, conducting good quality systematic re-views is not easy and difﬁcult to interpret. Since analysis of a data with meta-analysis is a relatively new field of research, many clinicians have not had the opportunity to learn about systematic review and meta-analysis systematically. An introduction of the rationale for carrying out meta-analysis will be helpful to the clinician in interpreting the results of meta-analysis.