Upon comparative evaluation of functional activity of bronchoalveolar lavage (BAL) cells and those of peripheral blood in patients with acute lung abscesses it was found that BAL cells reflect more pronounced changes in functional activity of immunocompetent cells. Investigation of immune status in acute lung abscesses demonstrated the significance of a clinical pattern of the disease and severity of purulent destruction. The relationship may be also inverse, i.e. the specific response of the immune system to antigenic loading ++pre-determines relevant form of the disease. The addition of pleural ++pyo-inflammatory side effects is probably due to phagocytic insufficiency. Functional derangements of phagocytic system are similar to those in gangrene though less distinct.