Data and safety monitoring committees (DSMCs) often are empanelled in randomized controlled trials (RCTs), especially multicenter trials, when primary end points include mortality and major morbidity. These committees periodically review safety and efficacy data and, based on their benefit-to-risk assessment, recommend to the sponsor whether the trial should continue and if so, whether modifications are necessary. Primarily, the DSMC must minimize risks to trial participants. Sponsors and investigators of RCTs help ensure external credibility by delegating oversight to an external committee. Although cultural differences may affect regional perceptions in the increasingly frequent multinational trials, external, independent DSMCs are accepted throughout the world.