Back ground: Despite advances in the control and prevention of nosocomial infections, itrncontinues to remain a major affectation in hospital treatment and contribute significantly tornthe high rate of morbidity, mortality and the health care of hospitalized patients in differentrnparts of the world.rnMethods : A prospective observational study with the aim of the study to determine thernprevalence of hospital acquired bacterial infection and their antimicrobial susceptibility wasrnconducted from April to August, 2009 at Felege Hiwot Referral Hospital, Bahir Dar. Onernthousand three hundred-eighty three patients, who had been admitted to surgical,rnGyaenacology and Obstetrics wards were included in this study were subjected to follow uprnthe diagnosis for HAI. Routine conventional microbiological diagnosis (Culture,rnbiochemical tests, gram staining and antibacterial sensitivity)were done for isolation ofrnpathogens from HAI patients. The questionnaire ---- were used for socio demographic datarnand to assess associated risk factors. Antibiotic susceptibility tests were done by using thernstandard Kirby Bauer disc diffusion method.rnResults: Among the total 1383 observed patients, 246 developed HAI with a prevalence ofrn17.8 %. The types of hospital acquired infections were UTI, 118 (48 %), SSI, 112(45.6%),rnBSI, 9(3.7%), pneumonia, 4(1.6%), and 3 (0.3%) developed mixed infections. Among therntypes of HAI UTI was the predominant followed by SSI and then BSI and pneumonia werernthe least type of HAI. Certain primary data collected from the HAI patients who werernpredispose to conditions like operation procedures, use of catheter, underlying diseases,rnantibiotics prophylaxis and length of hospital stay contributed as high risk factors based onrnstatistical significance (P= 0.0001). among the patients population. Gram negative bacteriarnwere the predominant organisms with 52.6% compared to gram positive bacteria 47.4%. Thernpredominant 49(37.1%)bacteria observed was E. coli when compared to other organismsrnsuch as K pneumoniae 36 (27.3%), P.aeruginosae 26 (19.7% ,P. mirabilis 10(7.6%),rnEnterobacter species 4 (3% )P. vulugaris 3 (2.3%)and both Acinetobacter baumannii andrnS.marcescens each accounted 2(1.5%) whereas among gram positive bacteria, S. aureusrn91(76.5%) was the commonest isolate followed by CoNS 18 (15.1% ), and Enteroccocusspecies 10 ( 8.4%). Most of the isolates were resistant to commonly prescribed antibiotics.rnMethicillin resistance S. aureus was for 94.5% and ampicillin resistance was 98.4%.rnConclusion: UTI, 118(48%)was the commonest Hospital acquired infection. SSI, (87.5%)was the commonest hospital acquired infection in surgical ward where as UTI, 58 (49.2)wasrnthe commonest HAI in obstetrics ward. Gram negative bacterial isolates were thernpredominant etiologies with intermediate to high resistance to commonly prescribedrnantibioticsrnRecommendation: Further studies are needed involving all wards including medical andrnpediatrics ward, as well as other causative agents anaerobic bacteria, fungal agents etcrnOrganizing an effective infection prevention program in the hospital and continousrnmonitoring and evaluation are essential.