Background: Nosocomial infections are defined as infections which are not present or notrnincubating when the patient is hospitalized and are acquired during hospital stay. Sign andrnsymptoms of the infection may be evident during hospitalization or after discharge related tornthe length of the incubation period. It is usually defined as an infection that is identified atrnleast 48-72 hours following admission to health institution. Infections acquired in hospitalrnare likely to complicate illness, cause anxiety and discomfort, and can lead to death.rnNosocomial infection is a global problem with multi facet out comes. The problem is wellrnpronounced in developing countries. Epidemiological and etiological characteristics ofrnnosocomial infections show variations among countries and even among different hospitalsrnin the same country. Many of these infections are associated with micro-organisms that arernresistant to multiple antibiotics and can easily spread on the hands of personnel. The mostrnfrequent types of nosocomial infections are urinary-tract infection, surgical-wound infection,rnpneumonia, and bloodstream infection. At present, the emergence of resistance tornantimicrobial agents is a global public health problem, particularly in pathogens causingrnnosocomial infections. Antimicrobial resistance results in increased morbidity, mortality andrnhealth-care costs.rnObjective: To determine the prevalence, etiological agents and drug susceptibility pattern ofrnnosocomial infections at Tikur Anbessa University Hospital.rnMethods: A cross-sectional study was conducted from June 2007 to April 2008 at TikurrnAnbessa University Hospital, Addis Ababa, Ethiopia. During the study, all adult patientsrnadmitted to surgical wards and SICU with suspected of nosocomial infection were included.rnAmong 854 patients admitted to surgical wards and SICU, 215 patients selected based onrntheir clinical ground, after a careful clinical examination. Clinical samples were collectedrnfrom the study subject and analyzed accordingly.rnResults: Eight hundred fifty four patients admitted to surgical ward and SICU between Junern2007 and April 2008 to Tikur Anbessa University Hospital in Addis Ababa were studied forrnprevalence of nosocomial infections. A total of 215(25.2%) patients, were selected based onrntheir clinical grounds from surgical wards (n=161) and SICU (n=54). The mean hospital stayrnfrom the date of admission until sample collection was 16.72 days with a range of 3 to 66rndays. Of the 215 patients, 130(60.5%) were males and 85 (39.5%) were females. A total ofrnnine percent (77/854) patients were confirmed to have nosocomial infections. Of the 77rnpatients, 51(66.2%) were males and 26(33.8%) females. The distribution of nosocomialrninfections among positive cases was surgical site infection 38(49.4%), urinary tractrninfections 23(29.8%) and blood stream infection 16(20.8%). The Gram-positive andrnnegative bacteria accounted for 23/84(23.4%) and 61/84(72.6%) respectively. A total of 84rnbacterial pathogens (strains) were isolated, E. coli accounted for 19.0% of the total isolatesrnfollowed by S. aureus and Klebseiella spp. More than one bacteria etiologic agent wasrnisolated from 7/77(9.1%) of the patients with nosocomial infection. Gram positive bacteriarnshowed 100% resistance to penicillin, ampicillin, tetracycline, chloramphenicol, andrntrimethoprim-sulphamethoxazole; while gram negative bacteria showed 100% resistance tornamoxicillin, Tetracycline and Trimethoprim-sulphamethoxazole.rnConclusion: The prevalence of nosocomial infection at Tikur Anbessa University Hospitalsrndecreased from the previous study (16.4% and 13%) in the same hospital. Gram-positivernbacteria isolated from nosocomial infection were 100% resistance to Ampicillin,rnTetracycline, Trimethoprim-sulphamethoxazole and Chloramphenicol. In addition, gramnegativernbacterial isolates were 100% resistance to Amoxicillin, Tetracycline andrnTrimethoprim-sulphamethoxazole. Due to the presence of high level drug resistancernbacteria, empirical treatment to nosocomial infections may not be effective. Therefore,rntreatment should be based on the result of culture and sensitivity.rnKeywords: Nosocomial infection, Surgical Site Infection, Blood Stream Infection, UrinaryrnTract Infection, Intensive Care Unit