The term health associated infection, health care associated infection,hospital acquired infection, hospital-associated infection, hospital infection or nosocomial infection is defined as infection developing in patients after admission to the hospital, which was neither present nor in the incubation period at the time of hospitalisation. Such, infections may become evident during their stay in the hospital or, sometimes, after their discharge. There are a lot of factors influencing infections such as susceptible patients, hospital environment, diagnostic or therapeutic procedures, drug resistance, transfusion, and advances in medical progress. Almost any microorganism can, on occasion cause hospital acquired infections such as Staphylococcus aures, E.Coli, Klebsiella sp, Pseudomonas sp, Enterobacter, Proteus, and Serratia. These microorganisms are transmitted through 4 main routes-Contact, Airborne, Oral route, Parenteral route. My talk will concentrate on the definition of Hospital acquired infection, common organism there disease pattern, Prognosis, treatment, Prevention and concluding with the Infection control policy followed in India.