ObjectiveTo realize situation of nosocomial infection （NI） in different scale hospitals in Inner Mongolia Autonomous Region.MethodsPrevalence rate of NI in patients in 40 hospitals were surveyed with the method of bedside checking and case history review.ResultsA total of 18 172 patients were surveyed, prevalence rate was 2.54% (462/18 172), case infection rate was 2.61% (474/18 172). NI sites were common in lower respiratory tract (42.14%), upper respiratory tract (22.15%), urinary tract (12.66%), superficial incision (9.28%), and gastrointestinal tract (3.80%). Prevalence rate was high in general intensive care unit (20/85, 23.54%). Antimicrobial use rate was 49.69% (9 029/18 172), rate for monotherapy and therapeutic usage was 66.94% and 47.56% respectively; Bacterial culture rate in patients with therapeutic usage was 14.63% (787/5 381).ConclusionThe average prevalence rate was 2.54% in 40 hospitals, lower respiratory tract was the major infection site, the main pathogen was gramnegative bacteria. Training on rational use of antimicrobial agents should be intensified, and pathogenic detection rate should be enhanced.