Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. However, there is increasing evidence that smokers have a lower incidence of some inflamma- tory and neurodegenerative diseases. Nicotine is the main immunosuppressive constituent of cigarette smoke, which inhib-its both the innate and adaptive immune responses. Unlike cigarette smoke, nicotine is not yet considered to be a carcino-gen and may, in fact, have therapeutic potential as a neuroprotective and anti-inflammatory agent. This review provides a synopsis summarizing the effects of nicotine on the immune system and its (nicotine) influences on various neurological diseases.