Respiratory infections account both for the majority of all human illnesses and bulk of human infections. This has been well supported by clinical, epidemiological, microbiological and serological data obtained by carefully controlled studies. Viruses are the causative agents in more than 90 percent respiratory infections while bacteria are responsible for the balance. Further there are significant differences between upper and lower respiratory tract infections also between children and adults. The respiratory tract infections are common in temperature and wet seasons. Laryngeal infections are common in dry-hot season. Overcrowding, malnutrition, age and sex are some of the influencing factors. About 2. 2 million deaths occur due to acute respiratory disease every year. If all causes of respiratory disease are taken into account, 61 percent of deaths due to respiratory illness result with acute respiratory disease.