Cigarette smoke contains numerous carcinogens (substances that may cause cancer), poisonous gases ( carbon monoxide and hydrogen cyanide) and other chemicals. One of these chemicals is called coal tar (brown stick substance) that collects in smoker’s lungs from where it passes into the blood. It also kills the cells of wind-pipe and lungs. Cigarette smoke also contains a strongly addictive drug called nicotine. Even 0.07 gram of nicotine in the blood can be poisonous. Many people think that lung cancer is only smoking-related diseases and it is the number one cause of death among smokers. but it is not right. Cigarette smoke affects the body from head to toe. Smokers have a much higher risk of developing a number of life-threatening diseases. Nicotine is a powerful poison and was widely used as an insecticide in the past. When inhaled through tobacco smoking, it reaches our circulatory system and not only hardens the walls of the arteries but also damages the brain tissues. Smoking may also lead to the cancers in kidney, oral cavity, larynx, breast, bladder and pancreas etc. many chemicals in tobacco smoke damage the air passageway, which leads to emphysema and other respiratory disorders. Non-smokers who exposed to second-hand smoke (passive smoke) at home or work increase their heart disease risk by 25-30% and their lung cancer risk by 20-30%. Smoking also lead effect on the circulatory system. The carbon monoxide present in tobacco smoke lessens the oxygen-carrying capacity of haemo-globin. Many others chemicals in smoke increase the production of blood platelets. When platelets are more than the normal numbers, they made the blood viscous and it can arteriosclerosis. Smokers are at greater risk of developing infections, particularly in lungs. For example, smoking increase the risk of tuberculosis by two to four times, and of pneumonia by four times. Smoking is also responsible for weakening and staining the teeth. Tooth loss is 2 to 3 times higher than in non-smokers. Smoking also affects the social life of a person. Smokers may face social un-acceptance because other may not want to be exposed to other’s smoke.