Health decisions should be according to the evidence from randomized controlled trials. These studies compare two or more effective interventions in a specific situation on the target population. When for a specific clinical problem in randomized controlled trial studies, the effect of at least three effective interventions is examined, meta-analysis can be used to combine the effect of the interventions and obtain a general estimate of that effect size in the target population; while for most clinical conditions, and there are more than two effective interventions. In such a situation, multiple meta-analyses are not possible. In addition, direct clinical trials may not have been introduced and used for all interventions. Network meta-analysis is a method to compare several interventions simultaneously in a single study by the combination of indirect and direct evidence in a network of randomized controlled trials, the findings of which provide the possibility of ranking different interventions. The current study was prepared with the aim of providing basic explanations regarding the benefits of producing a network based on indirect and direct evidence, conducting network meta-analysis, checking the main assumptions, and the stages of analysis.
