The objective of the present study was to estimate the informative value of the cytological investigation of nasal secretion in the children presenting with infectious and allergic rhinitis and sinusitis. This publication presents the results of comparative analysis of rhinocytograms obtained from the patients with the above diseases. It was shown that the rhinocytological technique can be applied for differential diagnostics of rhinitis and sinusitis in the children, the assessment of the severity of allergic diseases of the upper respiratory tract, and monitoring the efficacy of the treatment of rhinitis.