Electronic cigarette (e-cigarette) is a device developed with an intent to enable smokers to quit smoking and avoid the unhealthful effects of cigarettes. The popularity of e-cigarette has increased rapidly in recent years. The increase in its use during the adolescence period is attention-grabbing. Despite the fact that e-cigarette has become popular in a dramatic way, there are certain differences of opinion regarding its long-term effects on health, in particular. While some people assert that it is less harmful than conventional cigarettes, some others assert the contrary. Although e-cigarette contains less toxic substances compared to conventional cigarette, it contains certain carcinogens existing in conventional cigarette such as formaldehyde and acetaldehyde. It also contains heavy metals (nickel, chrome) that conventional cigarette does not contain; and therefore, raises concerns about health. E-cigarette leads to upper and lower respiratory tract irritation as well as an increased airway resistance and an increased bacterial colonization in the respiratory tract. It may also cause tahcycardia and increase diastolic blood pressure. Although e-cigarette has been found to have certain benefits in terms of smoking cessation, most of the studies have shown unfavorable results. In this collected work, the effects of e-cigarette on health and its role in smoking cessation are discussed in detail.