Asthma is characterized by chronic airway inflammation, extreme airway sensitivity and reversible as well as diffuse airway obstruction. Its incidence varies according to the regional variations. Its incidence is less than 5% in our country. Existing genetic profile and environmental factors lead to disrupted immune regulation and/or imbalanced neural control and/or induced non-immunogenic, non-neural pathway causing chronic inflammation in asthma bronchiale. Whichever event takes place first, causes the others to follow. All of the patological findings are reversible at first, but then they cause remodelling in bronchi. Medical history and physical examination establish the diagnosis; laboratory tests are supportive in diagnosis. İrritative cough, wheezing, sense of pressure on the precordium and shortness of breath are frequently encountered but not disease specific. Asthma is categorized according to etiology, clinical signs and respiratory function tests and hence the treatment is initiated accordingly.