Aims: To study the extent and pattern of use of antibiotics for prophylaxis in medical and surgical intensive care units. Subjects and Methods: 100 patients each from SICU and MICU were included inthe study. Case record files were analyzed daily until discharge from ICU or a maximum of 21 days. Details of all antibiotics prescribed for prophylaxis were recorded in a proforma, which were then analyzed using relevant statistical tests. Results: 65% patients in MICU and 99% in SICU received antibiotics (p value __ampersandsignlt;0.0001). Among patients who received antibiotics, 37% in MICU and 73% in SICU received them for prophylaxis (p value __ampersandsignlt;0.0001). Average duration of prophylaxis was 2.58 days in MICU and 3.14 days in SICU. 19 (79.14%) patients in MICU and 48 (66.67%) patients in SICU received prophylaxis for more than 24 hours (p value = 0.3690). 15 (62.5%) patients in MICU and 31 (43%) patients in SICU received combination of antibiotics for prophylaxis (p value = 0.156). Third generation cephalosporins were the most commonly prescribed antibiotics for prophylaxis in both ICUs. Conclusion: Widespread use of antimicrobial prophylaxis in ICUs with broad spectrum antibiotics and antibiotic combinations, with duration longer than recommended has emerged as area of concern in__ampersandsignnbsp;present study. Such surveillance studies help in recognition of areas requiring special attention, which can guide the formulation of antibiotic prescription policies at individual ICU level.