OBJECTIVES : To investigate Knowledge, Attitude and Behavior of antibiotic used in upper respiratory infection. 2. To identify factors affect the antibiotic used in upper respiratory infection.

METHODS : A cross-sectional survey study was performed at Burapha University in 2019. Sample size was calculated according to Hair et. Al, 2010. 360 students were randomly selected from 3 groups of students-medical sciences, pure-sciences, and social-sciences students. Self-administrative questionnaires were used to collect data.

RESULTS : Medical sciences students had significantly better knowledge, attitude and good behavior in using antibiotics than social sciences students (p=0.000, 0.000, 0.000, ANOVA, respectively). Knowledge of antibiotic significantly correlated with using behavior (+0.224, p<0.01). Attitude significantly correlated the used of antibiotic (+0.295, p<0.01). Knowledge also correlated to attitude in antibiotic used (+0.232, p<0.01). Predictive equation for antibiotic used behavior was established: Behavior = 0.21 Attitude** -0.2 Art** -0.17 Sciences* -0.1 Male* + 0.09 Knowledge + 0.03 Age + 0.01 Cousin – 0.01 pharmacist in family, (R Square = 0.088, Hierarchical Stepwise Multiple Regression Analysis)

CONCLUSIONS : Factors significantly predicted antibiotics used behavior were attitude, medical sciences students, pure-sciences students, and gender (p = 0.00, 0.00, 0.01 and 0.05, respectively). Attitude is the most influential factor to predict antibiotic used followed by social sciences students, gender, and have health care profession in the family.