Nosocomial infections are a major public health problem with a substantial impact on quality of life. Hospital-acquired infection is a cross infection of one patient by another or by doctors, nurses, and other hospital staff while in hospital. When patients receiving medical care may get nosocomial infections or infections related to healthcare both wealthy and poor nations around the world are affected by these illnesses. Nosocomial infections cause 7% of deaths in industrialized countries and 10 % in developing nations. As WHO (World Health Organization) estimates that 15% of people who are hospitalized these infections affect patients. Nosocomial infections may also be considered either prevalent or widespread. So at that time health workers, as well as a hospital, should be taken preventive measures for nosocomial infections. Here there are different criteria mentioned for the investigations of nosocomial infections and which are useful the detect hospital-acquired infections and hereafter mention the preventive measures for the patients as well as health workers. And also give correct preparation of hospital staff for biosafety, proper waste management and healthcare reforms and arranging general public awareness of these widespread infections can also help decrease nosocomial infections.