Therapeutic decision-making on a rational basis implies the need ofappropriately understanding the nature of the available evidence regarding treatment effects. Randomised clinical trial is the optimal study to impartially assess the risks and benefits of a treatment or intervention. In order to make a proper use of this information, users should be able to appraise the trustworthiness or risk of bias of the study (should I believe it?), understand and interpret appropriately the results (what is it really telling me?), and understand its practical usefulness (who can this results be applied to?).