The purpose of the present study was to evaluate the prevalence of oral mucosal lesions and conditions in a population in Ljubljana, capital of Slovenia. A total 1609 subjects represented the study population in the survey about the periodontal treatment needs in a population in Ljubljana, conducted from 1983 to 1987. Ten years later the same 1609 subjects were invited to the second examination. Altogether, 555 (34.5%) of the invited subjects in the age range 25-75 years came for an interview and clinical examination at the Department of Oral Medicine and Periodontology of the Dental Clinic in Ljubljana. Oral mucosal lesions and conditions were evaluated according to the WHO Guide to Epidemiology and Diagnosis of Oral Mucosal Diseases and Conditions. The results showed the presence of one or more mucosal lesions in 61.6% of the population. Fordyce's condition was observed the most frequently (49.7%) followed by: fissured tongue (21.1%), varices (16.2%), history of herpes labialis (16.0%), history of recurrent aphthae (9.7%), denture stomatitis (4.3%), leukoplakia (3.1%), cheek biting (2.7%), lichen planus (2.3%), frictional keratosis (2.2%), geographic tongue (2.2%), geographic and fissured tongue together (1.1%), mucocele (0.9%), smoker's palate (0.5%) and angular chelitis (0.4%). In the population examined, no oral malignancies were observed. Mucosal lesions like whitish lesions, denture related lesions, fissured tongue, varices and mucocele were more prevalent with increasing age. Tobacco-related lesions (leukoplakia and smoker's palate together) were significantly more prevalent among men than among women (P<0.05), while lichen planus, denture stomatitis and herpes labialis occurred more frequently in the female population.