Electronic cigarettes (e-cigarettes) were developed more than a decade ago to deliver nicotine into the human body through the respiratory diffusing surface. In e-cigarettes, nicotine is thermally vapourized, together with f lavourings, in a propylene glycol/glycerol vehicle („e-liquid“) by means of a battery-driven heating element. As a result, numerous pyrolysis products, which exert deleterious effects, are inhaled into consumers’ airways, in addition to the original constituents of the e-liquids. The current review concentrates on the pathobiological effects of the e-cigarettes on the airways and lungs with an emphasis on the molecular mechanisms leading to pathways and disease conditions that appear to be similar to those caused by smoking of ordinary cigarettes. In particular, gene toxicity and the mechanisms leading to oxidative stress and augmented inflammatory response, as well as changes in airway microcirculation and cellular metabolome, induced by e-cigarettes/e-liquids, are discussed.