The QT interval prolongation is an undesirable effect of many drugs from various pharmacological groups. In connection with the use of combined pharmacotherapy in many cases, the risks of developing and potentiating drug-induced QT prolongation and life-threatening arrhythmias associated with increase in this factor. Reduction in the risk of dnig-induccd QT interval prolongation increases the safety of pharmacotherapy. The review provides a summary of data on the mechanisms and conditions that are responsible for drug-induced QT prolongation and discusses the tactics of prescribing medications associated with the risk of long-QT syndrome development in terms of the possible prediction of this side effect, its prevention and elimination.