Introduction and Aim: Introduction and Aim: Irrational drug use causes numerous health problems such as treatment failure, drug-drug interactions and resistance development.Although efficiency of early rational drug use (RDU) education on future doctors is emphasized, studies about this subject is inadequate. Purpose of this study is to determine knowledge, opinion and behaviors of Marmara University School of Medicine (MUSM) pre-clinic students related with RDU.

Methods: Questionnaire containing demographic and multiple choice questions and consisting of 41 questions which depends on literature was performed to 1st, 2nd and 3th grade students of MUSM in this observational and descriptive study without using sampling methods. Four hundered and twelve results are achieved of 600 participants.Data of survey is analyzed by using SPSS v20.0, frequencies and mean values were calculated, in compearative analysis, chi-square and independent t-test were used.Statistical significancy was accepted as p<0.05. Ethics committee approval of MUSM was taken.

Results: Results: More than half of the participants (%51.9, n=214) were women, rest of them were men. Thirty two percent (n=132) of participants were first-year, 34% (n=140) were second-year and 34% (140) were third-year students. Thirteen point five percent (n=56) of students selected four principles of RDU correctly. Twelve point seven percent (n=32) of participants who described themselves as“aware of RDU” gave accurate answers when asked to choose right four principles. Correlation was not found between grade and knowledge of RDU among students (chi square,p=0.45). However, there was no meaningful difference in medication use without prescription whether or not knowing principles of RDU (chi-square,p=0.14). Ninety two point nine percent (n=381) of participants declared keeping used or new drug in their house; knowing RDU was not effective in this behavior (t-test, p=0,06). There was no meaningful difference in keeping antibiotics at home without being ill between first and third-grade students (chisquare,p=0,28). Sixty four point seven percent (n=264) of participants stated that RDU was not emphasized properly in faculty. Sixty five point fice percent (n=269) of students thought that education of RDU should be given at beginning of medical faculty in pre-clinic period.

Conclusion: It was understood that participants did not have sufficient awareness of RDU in their early classes and having knowledge of the RDU did not create a positive change in their behavior. Through medical education, an early and continuous education for RDU, which is spread over five to six years, can ensure the development of long-lasting attitudes and behaviors.