Tabacco smoking is a major public health problem. The evidence demonstrates that smokers are over-represented among the patients with severe diseases. Smoking in the significant way influence the prognosis related to the outcome of treatment and the length of stay in Intensive Care Units (ICUs). Recent studies confirmed that smoking has an independent dose-related adverse effect on mortality of critically ill patients. This review covers the issues connected with critically ill patients addicted to nicotine emphasizing the problems that could occur during their stay in ICU. Identifying patients at risk of complication at ICU may lead to earlier intervention in routine clinical practice.