Proper evaluation of up-to-date clinical evidence is essential for the provision of optimal patient care. Randomized controlled trials (RCTs) are the ideal study type to investigate the benefit or harm of an intervention, such as a drug therapy. RCTs aims to avoid biased assessment of clinical interventions through the even distribution of both known and unknown factors that may influence outcomes. However, not all RCTs are well designed, conducted or reported. As such, the clinician needs to critically appraise RCTs in order to determine their strengths and weaknesses. This paper aims to explain how to approach critical appraisal, by highlighting and illustrating important questions that help determine the reliability of results from randomized trials.