Drug usage increases with the age and becomes an important problem. Side effects and intoxications of drug, multiple drug usage, drug-drug interactions, changes in drug pharmacodynamic and pharmacokinetics are common due to cognitive problems such as forgetting and misunderstanding. As drug use related problems cause increase in mortality and morbidity rates, rationale drug use is very important in elderly. By preventing inappropriate drug use, rationale drug use decreases drug-related costs and increases life quality of elderly. Physician, nurse and all health professions have responsibilities in rationale drug use. The responsibilities of nurses within the context of rational drug use are having knowledge about pharmacodynamic and pharmacokinetic changes in old ages, educating elderly patient and his/her family about drug use for providing their compliance to drugs and monitoring drug side effects. Rational drug use in elderly and responsibilities of nurses in this context are discussed in this article.