Introduction: Open fractures are fairly common in developing countries. Causes of open fractures vary widely including road traffic accident, fall from height, gunshot, assault, machine injuries and others. Infection is a common complication of open fractures. Chronic osteomyelitis, nonunion, loss of function or even limb loss are some serious outcome of deep fracture site infections. Primary goal in management of open fractures is prevention of infection of bone and soft tissue by early debridement, irrigation of wound and administration of broad spectrum antibiotics with stabilization of fractures. Aim: The aim of the study is to elucidate pattern of microbial isolates in open fractures so as to form rationale antibiotic regimen for treating open fractures. Methods: 70 patients were taken into study of all ages, both the sexes with open fracture classified according to Gustilo Anderson classification. Primarily wound was examined and description of the wound was recorded with 1st culture swab taken at that time followed by 2nd culture swab on 1st dressing after debridement and 3rd culture swab if infection continues further. Culture and sensitivity reports were collected for studying pattern of bacterial isolate and their sensitivity. Results: Pre-debridement cultures are of no importance. Post-debridement cultures are important in formulating an antibiotic regime. Gram negative organisms are the most probable cause of infection. Aminoglycosides are the most sensitive group of drugs in both gram positive and gram negative bacteria. Cephalosporins or quinolones should be used in combination with aminoglycosides in all cases of open fracture in our vicinity. Conclusion: All institutions and hospitals should find out the most common infecting pathogen in their environment and formulate an antibiotic policy accordingly.