It is well known that smoking contributes to the development of lung cancer and cardiovascular disease, and there is weighty evidence that it has a considerable influence on oral health. Smoking has many negative effects on the mouth, including staining of teeth and dental restorations, reduction of the ability to smell and taste, and the development of oral diseases such as smoker’s palate, smoker’s melanosis, coated tongue, and, possibly, oral candidosis and dental caries, periodontal disease, implant failure, oral precancer and cancer. From a qualitative point of view the latter is obviously the most serious tobacco-related effect in the mouth. Quantitatively, however, importance has been attached to periodontitis, which affects a large proportion of the population, and during recent years more attention has been given to implant survival rates. Dentists have an important role to play in preventing the harmful effects of smoking in the mouth, and consequently smoking counselling should be as much a part of the dentist’s job as plaque control and dietary advice.