A hospital-acquired infection (HAI), also known as a nosocomial infection is an infection that is acquired in a hospital or other health care field. Hospital acquired infection are major complication in every unit of hospital, Specially, Critical Care Unit. Hospital acquired infection is burden for the society. This increased morbidity, mortality, cost of treatment and also hospital staying condition. Mostly patients, their relatives & health care provider get infected by the nosocomial infection. The main aims of this study were to assess magnitude of different hospital acquired infection (HCAI), duration of stay and antibiotic use in Critical Care Unit and also to assess the cleanness practice among doctors and staffs in Critical Care Unit.During the 2months period a total of 84 patients were admitted Santosh Medical college and Hospital for more than 48hours and were included in the study. In admitted 84 patients, 28 (33.33%) were confirmed and documented with nosocomial infection. Out of 28 nosocomial infected patients, that rate of urinary tract infection, respiratory tract infection, surgical site infection, intravascular infection and other was 15(53.57%) ,9(32.14%), 6(21.42%) ,8(28.57%) and 5(17.85%) respectively.