Asthma is a chronic inflammatory disease of the airways. Clinical manifestations of the disease are a result of increased intensitiy of the inflammation. Asthma is a heterogenous disease. It is believed that asthma is caused by combination of genetic and environmental factors. Main pathogenetic features of asthma are inflammation of the airways and bronchial hyperreactivity. Signs and symptoms of asthma vary. Periods of complete absence of symptoms alternate with exacerbations of the disease. Many tests are being used in diagnosis of asthma, but none of them are sufficiently sensitive nor specific enough. Lung function tests have the most value in diagnosing and assesing the severity of asthma. Treatment of asthma requires a comprehensive plan that includes general measures, drug therapy and patient education. Corticosteroids are considered to be the most useful drugs in disease control, and short – acting beta2-agonists are most common medication used for the temporary relief of symptoms. Patients are treated according to GINA guidelines. Asthma is one of the most common chronic diseases in the world. As of 2011, 250–300 million people worldwide are affected by asthma, and approximately 250,000 people die per year from the disease. The prevalence and incidence of asthma in recent decades are increasing in both children and adults. The prevalence of asthma in the world is currently between 1-18%. Higher prevalence is observed in countries with higher economic standard. Although mortality from asthma has been reduced in recent years, it still exists. It is believed that asthma is the cause of 1/250 deaths in the world. Asthma is fifth in the world in health care costs and has a large significance in public health. The prevalence of asthma in Croatia ranges between 5-8% in children, and it is assumed that the prevalence in the general population ranges between 3-4%. Asthma is responsible for approximately 0.13% of all the deaths in Croatia, and the age-standardized death rate was 0.86/100,000. Asthma is considered a global problem and the "burden" to the population. Future research of the causes of asthma and implementation of primary and secondary prevention methods is the key strategy for reducing morbidity and mortality of asthma.