Background: Surgical site infections (SSI) comprise up to 20% of all healthcare-associated infections. The role of Acinetobacter in surgical site infection is increasing.The rising incidence of Acinetobacter infection in patients with immature or defective body defense system cause a great concern to all clinicians worldwide due to their extraordinary ability to develop resistance to multiple classes of antibiotics which limit array of the therapeutic options. Objectives: Our objectives are to Study microbiology in surgical site infection, Study role of Acinetobacter in surgical site infection and to identify multi-drug resistance Acinetobacter by MDR CHROMagar Acinetobacter confirmed by detection of OXA 51 by PCR. Methods: Samples collected from infected patients in orthopedics unit of EL Helal Hospital were subjected to direct microscopic examination and culture on blood, MacConkey and MDR CHROMagar Acinetobacter media. Susceptibility patterns were done by Modified Kirby Bauer disc-diffusion method.PCR was done for OXA51like detection from MDR isolates of Acinetobacter. Results : Out of 100 inpatients suffering from infections, 90 % (no=90) were found to be orthopedics surgical site infection. Implant was the major risk factor in SSI cases (89%),while diabetes mellitus (D.M) (20%) and obesity (14%). From 90 SSI cases 119 clinical isolates of different organisms were isolated. Staph aureus was the predominant organism in SSI cases (33.6%), followed by K. pneumoniae(18.4%) and A. baumannii and E. coli (12.6%for each). Prolonged stay in hospital was significantly associated with SSI (p = 0.001). The most effective antibiotics were, imipinem, sutream (33.3% for each) and meropnam (26.7%). PCR for detection of OXa 51 like gene was positive in (93%) (13/14) of MDR Acinetobacter isolates that were detected by choromagar. Conclusions: Orthopedics surgical site infection represent 90% of sample collected from El Helal hospital.Presence of implant is the major risk factor present.MDR Acinetobacter CHROMagar was 92.85% sensitive and 100% Specific in detecting MDR Acinetobacter which is confirmed by positive PCR OXA 51.