Introduction: How evident is the evidence?

Randomized-controlled trials (RCTs) and meta-analyses are the pinnacle of evidence-based medicine, enabling identification of the best available diagnostic, interventional, and therapeutic options. These tools help clinicians and policy-makers to set clinical guidelines, but they also represent a double-edged sword: the meaningfulness of RCTs and meta-analyses relies on their quality, performance, and integrity. The present Views and Reviews collection prepared by 18 renowned experts and coordinated by Ben Mol aims to inform and educate our readers about RCTs and meta-analyses in reproductive medicine. The collection begins with the basic features that guarantee the quality of a trial, including protocols, registrations and monitoring, study design and analysis, and reporting standards. Next are discussed the status of planning and coordination of RCTs in different global settings, current unmet needs, and how future studies can better meet these needs, as well as methodologic issues facing different types of RCTs. Finally, insight is provided into the issue of data fabrication and falsification, offering possible solutions to ensure the integrity of RCTs. The challenges and benefits of these crucial evidence-generating tools deserve our attention and education because the findings of RCTs and meta-analyses can directly affect the health of our patients, and when performance and integrity problems exist, the "magic" of these tools disappears-with harmful consequences.