Leukoplakia is the most common potentially malignant disorder of the oral mucosa. The prevalence is approximately 1% while the annual malignant transformation ranges from 2% to 3%. At present, there are no reliable clinicopathological or molecular predicting factors of malignant transformation that can be used in an individual patient and such event can not truly be prevented. Furthermore, follow-up programs are of questionable value in this respect. Cessation of smoking habits may result in regression or even disappearance of the leukoplakia and will diminish the risk of cancer development either at the site of the leukoplakia or elsewhere in the mouth or the upper aerodigestive tract. The debate on the allegedly potentially malignant character of oral lichen planus is going on already for several decades. At present, there is a tendency to accept its potentially malignant behaviour, the annual malignant transformation rate amounting less than 0.5%. As in leukoplakia, there are no reliable predicting factors of malignant transformation that can be used in an individual patient and such event can not truly be prevented either. Follow-up visits, e.g twice a year, may be of some value. It is probably beyond the scope of most dentists to manage patients with these lesions in their own office. Timely referral to a specialist seems most appropriate, indeed.