Allergic diseases are increasingly becoming a global epidemic and pose a considerable and growing public health burden. Allergy is a systemic T2-dependent inflammatory reaction to an allergen that results from a complex interaction between genetic and environmental factors. Allergic diseases occur through a T2-dependent type of allergic reaction, some of them, in particular atopic dermatitis (AD) and asthma, develop involving different types of hypersensitivity or their combination and require revision of allergy diagnostics. Atopy patch test (APT) can be informative in establishing a role of cell-mediated hypersensitivity in pathogenesis of allergic diseases. The review presents the recent data on the significance of APT in the diagnostics of skin and respiratory allergies.