Open leg fractures account for 5 to 10% of all fractures. They are prone to numerous complications, particularly infection. Their emergency management is medical and surgical. We conducted a prospective cohort study of patients with open leg fractures over a 6-month period from 17 May to 30 September 2015. Fifty-seven patients were included in the study. The infection rate was 19.3% (11 cases). Gustilo type III fractures (RR = 13.75) and externalization of the bone (RR = 3.52) were identified as infectious risk factors. A very high C-Reactive Protein level of more than 100 mg/l in the first week predicted the occurrence of an infection. Pseudomonas predominated (33.33%), followed by Staphylococcus aureus (20%). Multidrug resistant bacteria had a high proportion (40%). Sensitivity to Gentamycin and third generation Cephalosporins was good. In conclusion, apart from bone stabilisation, surgical debridement combined with antibiotic prophylaxis is essential to minimise the risk.