With the development of new therapeutic strategies, it is becoming increasingly difficult to develop drugs that show better efficacy. That is why new treatments are being sought that have similar efficacy, but in other respects show better quality. This trend stimulates the development of clinical trials aimed at demonstrating that experimental treatment is not (much) worse than control treatment. Such studies are called noninferiority trials, which we describe in this paper in relation to superiority trials and equivalence trials. We also pay attention to the problems you may encounter when conducting noninferiority trials.