Atopic dermatitis (AD) — one of the most common chronic dermatoses, which is often complicated by secondary fungal or bacterial infection. AD symptomatology frequently conceals clinical manifestations of skin mycosis followed by significant difficulties for timely diagnosis and treatment. Moreover, the use of topical glucocorticosteroids for AD treatment leads to significant changes in the clinical picture of dermatomycosis, that also complicates diagnostic search. We present a clinical case report of a patient suffering from AD, who consequently underwent smooth skin mycosis, then scabies. Diagnosis of skin mycosis was confirmed both clinically and laboratory, scabies — only clinically. Considering the clinical signs of scabies, the patient was treated (ex juvantibus) with an acaricidal drug, which resulted in almost complete rash regression. It should be emphasized that clinical examination plays a fundamental role in the diagnosis of diseases. In this case, it was the knowledge of the clinical picture features of both AD and scabies that allowed to suspect and establish a correct diagnosis, which was the basis of the selected therapy. Thus, a comprehensive approach to the diagnosis and treatment of infectious complications of AD, including both precise clinical examination and application of modern methods of laboratory tests, combined with a high level of patient’s compliance, allows to achieve optimal treatment results and significantly improve the quality of life of patients.