One of the objectives of this short communication was to add to the literature on the prevalence of oral recurrent aphthous stomatitis (ORAS). This research is based on a total of 11, 697 randomly selected Malaysian subjects with an age range of 25-115 years and a mean age of 44.5±13.9 years who were examined for oral mucosal lesions (ORAS). The prevalence of ORAS detected during the oral examination (average point prevalence) was found to be 0.5% (64 subjects). ORAS formed 5.7% of all lesions detected during the survey. The average point prevalence of ORAS was highest in the indigenous people of Sabah and Sarawak (1.2%), followed by the Chinese (0.7%), the Malays (0.5%) and the Indians (0.1%). This difference was statistically significant (p < 0.001). A review of the English literature on the prevalence of ORAS revealed different prevalence types used by different researchers, namely average point prevalence (APP), self reported life-time prevalence (SLP) and self reported two-year prevalence (STP). The other objective of this paper was to present the different types of prevalence that have been reported in the literature and to discuss the usefulness of such prevalence types in relation to using epidemiology in deriving certain possible etiological associations. (J. Oral Sci. 42, 15-19, 2000)