Oral disease is a major health problem worldwide, and in Ethiopia there is very little epidemiological research done in this field in recent times. This study was carried out to provide baseline information on the major oral health problems (dental caries, periodontal disease, malocclusion, and dental fluorosis) among school children in Addis Ababa. The study was school-based cross-sectional by design. It was conducted in April 2000 with the objective to determine the oral health status of school children who are 12 years and above. A total of 1736 study subjects were selected through a multi-stage sampling procedure from three different categories of schools (private, public and government), proportionate to their respective size of student population. The prevalence of dental caries was determined to be 21.1% and it was found to increase significantly with increasing age, high consumption of sweets, and in those who do not clean their teeth regularly. Periodontal disease affected more than half (53.4%) of the study subjects and was significantly higher in males, those with high consumption of sweets, and those having 'Injera' as staple diet, and those with poor oral hygiene. The prevalence of malocclusion was 23.7%, while crowding and spacing of teeth were found in 23.8% and 18.3% of the subjects, respectively. The prevalence of dental fluorosis was low (1.6%). Health education programs, about healthy diet and practices of adequate oral hygiene, should be promoted in schools through integration into the school curriculum and services.