The aim of this study was to determine the level of knowledge and behaviours of veterinarians in rational use of antibiotics, to raise awareness, and to determine the situation between human and veterinary medicine disciplines. This descriptive cross-sectional study was conducted face-to-face with 277 veterinarians working in clinics and farms in Izmir. In the questionnaire form, 24 questions including socio-demographic characteristics and rational antibiotic use were asked. Among the veterinary medicines, 82.3% had never received training on rational antibiotic use and 86.6% wanted to receive training. 63.5% of the participants stated that they prescribed and administered antibiotics requested by animal owners very often or frequently. Conditions such as antibiotic allergy, liver and kidney diseases were less important than human physicians. It was determined that they showed a rational approach to the patient owner about the method of application of antibiotics, duration of treatment, and when to stop, but they were deficient in the issues of side effects and interaction with other drugs. Antibiotics, when used rationally, can show their effectiveness in the future. In this study, it was determined that knowledge and behaviour of veterinarians about rational use of antibiotics were inadequate. The rate of those who demanded training on this subject was quite high. It is concluded that rational use of antibiotics can become widespread through trainings to be organised with the coordination of public and private institutions.