Background. Acute upper respiratory tract infections (AURTIs) are common in children and can become recurrent, especially in patients with pharyngeal and/or palatine tonsil disorders. Aim. To evaluate the efficacy and safety of the herbal medicine of marshmallow root, chamomile flowers, horsetail herb, walnut leaves, yarrow herb, oak bark and dandelion herb (Tonsilgon N) in preschool children with adenotonsillar disorders. Materials and methods. The study included 1876 children aged 2 to 5 years with a history of pharyngeal and/or palatine tonsil disorders and frequent recurrent respiratory infections. The subjects were randomized into two groups: Group 1 (n=940) received herbal medicine (10 drops 56 times daily) for 30 days, and Group 2 (n=936) received no additional medication. Efficacy and safety were evaluated after the therapy course and during the follow-up (3, 6, and 12 months after the treatment started). The assessment included nasopharyngeal endoscopy, cytological examination of nasal mucosa smears, measurement of soluble immunoglobulin A (sIgA) levels and lysozyme activity in nasal secretion. Results. After a course of therapy, a significant decrease in the incidence of AURTIs (p0.05), associated with a local immunity improvement, estimated by sIgA levels and lysozyme activity (p0.001 for both values versus the control group), was noted. By the end of the study, in 86.5% of patients of Group 1, the pharyngeal tonsil volume decreased from grade 2 to grade 1 of hypertrophy (p=0.000). The pharyngeal and palatine tonsil hypertrophy worsened in 83.6% of Group 2 patients. Conclusion. The study results showed that Tonsilgon N significantly reduced the incidence of AURTIs in children with pharyngeal and/or palatine tonsil disorders and frequent recurrent respiratory infections. This effect was associated with an increase in sIgA and lysozyme levels in the nasal secretion and a decrease in neutrophil counts, indicating an improvement in local immunity.