Objective: To assess the prevalence of dental caries and treatment needs of 12-year-old children living in Teheran and a rural area surrounding Esfahan. Subjects and Methods: A total of 1,102 pupils were examined clinically for caries according to WHO criteria. One calibrated dentist examined all children. Results: Of the children studied, 63.8% had sound permanent dentition, 9.9% had filled teeth and 26.3% needed treatment. The mean DMFT value found was 0.77 (DFS: 1.19). The D component was 58.7%, the M component 3.4% and the F component 37.9%. The levels of caries experience varied according to the child's residence. The teeth of children living in the rural area ( mean DMFT: 0.38) were significantly less affected than those of children living in Teheran ( mean DMFT: 1.1). In the capital city of Teheran, considerable differences related to social status were observed. The lowest DMFT values (0.74) were found in southern Teheran where the poorest people live. The highest caries experience was found in the middle-class social stratum. Conclusion: The results indicate that caries prevalence among 12-year-old children in the Islamic Republic of Iran is as low as in the developed countries of central Europe. Copyright (C) 2006 S. Karger AG, Basel.