Cigarette smoking effects all organs of the body harmfully and causes various diseases including respiratory system cancers such as larynx, esophagus, lung; chronic diseases such as cataract, coronary heart diseas, diabetes, tuberculosis etc. Nicotine gums, nasal sprays, patchs, lozenges and electronic-cigarettes have been used for a while to avoid the toxic effects of cigarette and quit smoking.  E-ciga are nicotine delivery systems electronically. An e-cigarette, which looks similar to traditional cigarettes, cheroots or pipes generally, is composed of a simple rechargable battery and a solution including nicotine, propylene glycol used as a solvent, water, flavoring and colorant agent. The working principle of the e-cigarettes is based on inhalation of nicotine and other excipients which are turned into steam by heat. Several studies have shown nicotine to be harmful to cardiovascular and central nervous systems. Immediately dangerous to life or health concentration is 5 mg/m3 for nicotine based on acut oral toxicity data on human according to NIOSH. Propylene glycol which is used as a food additive to absorb excess water and maintain the humidity classified as "generally recognized as safe" by FDA. Furthermore, it has been used as an antifreeze, ingredient in cosmetics and drugs and has not been classified as carcinogenic by IARC. Adverse health effects are likely to occur when the plasma concentrations of propylene glycol reach over 4 g/L. Several studies indicate that it has caused irritations on respiratory system; mouth, throat, pharynx. However, human studies are inadequate and the amounts and ingredients of e-cigarettes are unknown. Therefore, lung function effects, carcinogenicity and safety profile of e-cigarettes aren't expressed. Due to this contradiction, further studies are needed to assess potential health effects of e-cigarettes.