The cigarette smoke-induced rat model of chronic bronchitis was used to study the time course of the return of cigarette smoke-induced secretory cell hyperplasia to the normal and the capacity of two non-steroidal anti-inflammatory drugs to speed this recovery. Cigarette smoke alone significantly increased (P less than 0.05) the number of secretory cells in all of the eight airway levels studied to between 52-225% above control values. After cessation of exposure, recovery was complete by 9 days in the trachea, between 10-21 days in 'proximal' intrapulmonary airways and 43-84 days in distal bronchioli. Indomethacin and flurbiprofen, given by intraperitoneal injection at 4 mg/kg body weight for 21 days of the recovery period, significantly reduced the time taken for recovery to between 4 and 9 days in intrapulmonary airways but had no effect in the trachea.