Pidotimod is a synthetic dipeptide with immunomodulatory properties. An immunostimulant used in patients with cell-mediated immunodepression during resp and urinary tract infections. In vitro and in vivo laboratory studies show that treatment with pidotimod causes a significant induction of macrophage and neutrophil polymorphonuclear activity, which is characterized by an increase in spontaneous chemotaxis, superoxide anion production and phagocytosis. Several placebo-controlled trials of the drug have been carried out in various indications such as recurrent respiratory, pharyngotonsillar and urinary infections in children, and in adults with exacerbations of chronic bronchitis. For example, in 120 children with recurrent respiratory infections, pidotimod reduced relapse by 35%, hospitalization by 86% and antibiotic use by 47% compared to placebo.