Purpose: Few longitudinal studies on changes of decayed, missing, or filled teeth (DMFT) counts in a population have been reported. This study aimed to evaluate the changes in DMFT counts in Ljubljana citizens in a 30-year period. Materials and Methods: 238 dentate subjects that attended the third epidemiological study were invited. Ninety 45–95-year-old subjects (37.8%) responded to our invitation. Two (2.2%) edentulous subjects were excluded. Among the dentate subjects there were 28 men and 60 women. They were divided in six age groups with mean age of 45, 55, 65, 75, 85, and 95 years. The number of subjects in each age group was: 29, 12, 21, 18, 7, and 1, respectively. For evaluation of the state of teeth we used the DMFT index. Results: The average DMFT value for 45–95-year-old population was 19.3. Mean DMFT counts in all comparable age groups (45-, 55- and 65-years) decreased in 30 years. In 45 year olds they decreased from 17.5 to 15.7, in 55-year-olds they decreased from 20.4 to 19.2, and in 65 year olds they decreased from 22.5 to 20.7. An increase of the average number of present teeth (for 6.4 teeth in average) from the first to the fourth study in subjects of the same age was seen. Conclusion: Dental health in Slovenia has improved in 30 years. Average DMFT counts in subjects of the same age (45-, 55- and 65-years) have decreased. Ljubljana citizens have less decayed, less missing and more filled teeth than 30 years ago. Keywords: epidemiological study, teeth, DMFT counts, subjects