In infants, bronchial asthma is a rare disease. According to Debre (1952), 10-15% of asthmatic diseases appear already in the first year of life, but most asthmatic cases occur in the 2nd and 3rd years of life. In Slovakia, asthmatic diseases hardly occur in one-year-old children, and if they do, they are very rare. If they develop in infants, they have an atypical appearance and course. In infancy, a catarrhal form of asthma is mainly observed. It may be preceded by a runny nose, or it may occur with alarming speed. Fever can be high and persistent. Choking is intense and uninterrupted. Polypnoea with aular breathing develops. The cough is continuous, annoying, can turn into attacks. These threatening symptoms can pass away or weaken in a short time. Fever, polypnoea, cough, sonorous and moist rales and whistles continue for many days until the disease goes away, or after a weakening of symptoms a febrile asphyxiation crisis develops. Noisy, labored breathing and musical sounds heard with it are often blocked by rough creaks or purring sounds, which are usually considered transferred from the upper respiratory tract, or it is believed that they come from the trachea and large bronchi. Therefore, both with a typical and atypical or constant diploma of breathing in infants, it is first necessary to exclude or prove the remaining possibilities, but with clinical suspicion and with a suspicious family history, symptomatic anti-asthma treatment should be started. True, during an asthmatic attack in infants it is not necessary to have constant whistles and hoarse breathing. It must be recalled that the asthmatoid state can develop with some non-bacterial pneumonia, sometimes with a febrile or subfebrile course and with shortness of breath, hoarse breathing and with whistles in the lungs. Sometimes common pneumonia can simulate asthma. It is incorrect to make a diagnosis based on the absence of fever, since in infants and young children uncomplicated asthma can occur at elevated temperatures. The catarrhal period of measles also sometimes simulates asthma. But the main role in this case is played by endobronchial foreign bodies, tracheal compression by a hyperplastic thymus, vascular abnormalities, nodes, bifurcation adenopathy, perforating lymphadenitis, sublingual laryngitis with edema, laryngotracheo-bronchitis, perforated bronchopulmonary carcinoma, , whooping cough, eosinophilic or allergic pneumonia, papillomas, etc. With whooping cough, the diagnosis is difficult because cal infants and young children have a spasmodic cough, like whooping. Whooping cough, mainly in infants, can create an asthmatoid picture. In immunized infants, a disease diffusely localized in the small bronchi may be accompanied by hoarse breathing with prolonged expiration. It happened that with a differential diagnosis, difficulties arose due to bronchotetia, sometimes accompanied by atelectasis (Lederer 1913, Gottche 1928). Various infections and toxins can cause a neurogenic spasm of bronchioles, along with other dysenteric toxins (Pitsky 1956).