OBJECTIVES: To analyse the antibiotic consumption pattern in hospital acquired pneumonia (HAP) patients in a tertiary care teaching hospital METHODS: A prospective observational study, carried out in a tertiary care teaching hospital from January 2011 to  December  2012. HAP patients who fulfill the inclusion criteria were identified and enrolled into the study after taking informed consent. Patients were followed from the day of diagnosis of HAP, till the day of discharge or death.  Patient data like demography (age, sex), antimicrobial agents used (dose, duration of treatment), length of hospital stay and clinical outcome were recorded in a predesigned  data collection form. The cost of antimicrobial therapy was recorded from the day of admission till the day of discharge. Antibiotic consumption was calculated using defined daily dose (DDD) methodology. RESULTS: Total 310 patients were included in the study. Among study population 229 (73.9%) patients were male and mean age was 55.9±18.4 (mean±SD). Out of 310 patients 218  were improved, 37 were worsened or discharged against medical advice and 55 were expired.  Mean length of hospitalization was 9.45±6.75 (mean±SD) days. Total  27 antimicrobial agents were used for the treatment pneumonia among these patients. Among these antimicrobial agents,  consumption (DDD/100 bed days) was highest for piperacillin-tazobactum (parenteral, 0.12) followed by ceftriaxone (parenteral, 0.10), azithromycin (oral, 0.10) and trimethoprim-sulphamethoxazole (oral, 0.08). The percentage of treatment success was highest among patients treated with piperacillin-tazobactum+macrolide combination (10%)  followed by cephalosopin+macrolide combination (8%). However the cost of treatment was high for piperacillin-tazobactum+macrolide regimen CONCLUSIONS: This study provides estimate of quantities of different antimicrobial agents used in the treatment of hospital acquired pneumonia. Piperacillin-tazobactum (parenteral) is highest consumed among 27 antimicrobial agents. Since percentage of treatment success is almost similar for piperacillin-tazobactum+macrolide combination (10%) and cephalosopin+macrolide combination (8%), use of cephalosopin+macrolide combination should be encouraged in susceptible patients considering the lesser cost.