The effect of cigarette smoke on the upper aerodigestive tract is well known. On the other hand, the exact effect of laser smoke on the tracheobronchial tree has not been well analyzed. The aim of this study was to throw some light on the effect of cigarette smoke and laser smoke on the larynx and tracheobronchial tree in rabbits. Seventy two rabbits were included in this study and they were divided into 3 groups, group A (32 animals) exposed to cigarette smoke, group B (32 animals) exposed to laser smoke and group C (8 animals) was a control group. According to the duration of exposure groups A and B were further subdivided into 4 subgroups, each contained 8 animals. The rabbits were killed in different periods of time after exposure. Dissection and light microscopic study were performed. Inflammatory changes were noticed in groups A and B after single exposure and were found to increase proportionately with prolonged time of exposure. Carcinogenic effect was observed in both groups after long term exposure |