—Pneumonia was an inflammation that occurs in the lungs accompanied by exudation and consolidation of microorganisms. In Indonesia, the prevalence of pneumonia continues to increase. Treatment of pneumonia uses antibiotic therapy. The use of antibiotics needs to be controlled by evaluating the quality of antibiotic use to prevent negative effects that can occur on patients, such as antibiotic resistance. The purpose of this study was to determine the rationality of antibiotic use in pneumonia patients. This study did with an observational method with a cross-sectional design. The study was conducted in August-September 2019. Qualitative evaluations did with Gyssen method. The results of 35 medical record samples that fulfill the criteria showed that 13,24% of cases category 0; 10,29% of cases category I; 0% of cases category II C; 20,59% of cases in category II B; 2,94% of cases category II A; 0% of cases category III B; 0% of cases category III A; 0% of cases category IV D; 11,76% of cases category IV C; 2,94% of cases category IV B; 38,24% of cases category IV A; 0% of cases category V; 0% of cases category VI. Rational cases (category 0) were 13,24% and irrational cases (categories I-IV) were 86,76%.