To explore factors related to quality of mastication, information about teeth status and self-assessed health status were obtained by a self-administered questionnaire from participants in a dental screening program. Invitation letters for participation in the program were distributed by members of the neighborhood association to 1.275 residents of a town in Gifu prefecture aged 65 years or older. Participation rate in the dental screening program was 40.5%. A total of 513 participants (245 males and 268 females) completed the program and the questionnaire. The results were as follows. 1. Overall, 32% had 20 teeth or more and 88.4% had bridge(s) and/or denture(s). 2. The mean number of remaining teeth were 12.9 for males and 12.5 for females. There was no statistical difference in the number of remaining teeth between males and females. The mean numbers of remaining teeth among those aged 65-69 years was 15.7 and two thirds of them had lost the Lower First Molar. 3. Those who reported to be satisfied with their present mastication were 83.3% of men and 86.3% of women. The proportions were not influenced by age or sex. 4. Quality of mastication was related to self-reported "good physical condition' and "not easily tired'. 5. The proportion of those satisfied with their mastication was large in the groups with remaining teeth index 0-8 and > or = 17, and small in the group with remaining teeth index 9-16, showing a U-shaped curve for satisfaction rate against remaining teeth index. These results suggest a relationship of quality of mastication on health status. The importance of primary dental care for the elderly persons is underlined.