Wheezing is a common condition in pediatric practice, it can be defined as a musical sound, high-pitched and continuous, emitting from the chest during breath exhalation. Although almost 50% of children experiences wheeze in the first 6 years of life, only 40% of them will report continued wheezing symptoms after childhood. The classification of wheeze in preschool children is more difficult compared to school aged children. It is based on the onset and duration of symptoms and divided children in three categories: transient early wheezing, non-atopic wheezing and atopic wheezing/asthma. History and physical examination, skin prick test, exhaled nitric oxide, lung function test are the parameter to evaluate children with wheezing. The aim of management of wheezing is to finalize the control of symptoms, reduce exacerbations and improve the quality of life. All guidelines underline the complexity in making a diagnosis of asthma under five years and the need to identify phenotypes that may help paediatricians in the therapeutic choices.