In this survey, the experiences with and implications of a revised definition of oral leucoplakia are described. One of the new aspects of the revised definition is the distinction between a provisional, clinical diagnosis and a definitive one for which histopathological examination is required. A prevalence study of white lesions of the oral mucosa among a selected population of 1000 consecutive patients from the Netherlands showed a prevalence of a provisional and definitive diagnosis of oral leucoplakia of 0.6 and 0.2%, respectively. For uniform reporting, a recently proposed classification and staging system has been used to stage leucoplakias with a definitive diagnosis. The use of the revised definition of oral leucoplakia, as well as the classification and staging system, seem very suitable for epidemiological studies.