Childhood asthma is a widespread health problem because of its epidemic prevalence, as asthma affects more than 300 million people worldwide. Results from cross-sectional and cohort studies show that asthma starts in childhood in a large proportion of cases. A proper diagnosis is easier to make in adults and school-age children, as permanent changes in lung development, the strong impact of environmental factors on the airways, the immunologic maturity process, and the use of some diagnostic tools make asthma more difficult to diagnose in preschool children. This period of a child's life is an interesting challenge for pediatricians and specialists. The aim of the present review is to analyze the current knowledge regarding making an early and accurate asthma diagnosis and therefore deciding on the correct treatment to gain control over asthma symptoms and minimize health risks.