Both overweight or obesity and cigarette smoking are relevant risk factors for public health. Cigarette smoking is associated with lower body weight while smoking cessation is associated with weight gain. Most smokers who quit experience a weight gain, particularly within one year, and it may persist up to 8 years after smoking cessation. However, only a minority of quitters gain excessive weight. Some individual characteristics have been found to be associated with excessive weight gain after smoking cessation while methodological problems may affect estimates of weight gain observed in different studies. Main mechanisms to explain weight gain after smoking cessation include increased energy intake, decreased resting metabolic rate, and decreased physical activity. The health benefits of smoking cessation far exceed any health risks that may result from smoking cessation-induced body weight gain. As weight gain may be a barrier against quitting smoking or a reason to restart smoking, behavioural and pharmacological methods have been evaluated to control weight gain after smoking cessation. Physicians should apply efficient strategies to promote smoking cessation on their weight-concerned smoking patient. This review briefly addresses some issues on the relationship between smoking cessation and weight gain, with regard to the size of the problem, mechanisms, health risks and control strategies.