The article contains the information about pro- and anti-inflammatory cytokines in infants with acute obstructive bronchitis and thymus hypertrophy. The content of IL-6 and IL-10 has been de- termined in 101 children in acute period of disease and during early convalescence. It was found the increasing of production of proinflammatory IL-6 and a low level of anti-inflammatory IL-10 in the first days of illness in all children with thymomegalia. During convalescence in patients with acute obstructive bronchitis and thymomegalia IL-6 level was decreasing, and the level of IL-10 was in- creasing, but it did not amount to the level of healthy children.