Smoking and nicotine dependence are still one of the main reasons for a number of serious and life-shortening somatic diseases. At the same time, they are more prevalent in mentally ill individuals than in the general population. This work, which constitutes the first part of recommendations of the Polish Psychiatric Association, presents the scale of the phenomenon in the general population and among people with psychiatric disorders, diagnostic criteria of nicotine dependence and nicotine withdrawal. It discusses the impact of smoking and exposure to cigarette smoke on the development and course of psychiatric disorders as well as on the treatment of psychiatric disorders, including interactions between nicotine and psychotropic medications. Many psychiatric patients can reduce smoking or achieve complete abstinence if they are offered adequate motivation and therapeutic support. Contrary to popular belief, smoking cessation and nicotine dependence treatment do not negatively affect the symptoms of psychiatric disorders; patients’ mental conditions can improve following smoking cessation therapy. The best results in terms of maintaining abstinence are achieved with a treatment approach that combines pharmacotherapy with psychotherapeutic intervention integrated into routine psychiatric care.