Infection is on of the major problems in the critical care units. Even when antibiotics are given either for prophylaxis or treatment; the rate of infection is still high due to many factors like decreased immunity, more nursing manipulation and the use of various invasive procedures.The aim of this work was to study if there is a relationship between the organisms infecting the patients and those present on the surrounding media. All cases were subjected to : careful history taking , full clinical examination , plain chest x – ray , collected samples from patients of air were cultured on both blood and sabaru agars. There was a relation between the types of organisms in the ICU and those affecting patients.