Study was to assess knowledge, attitude and practice about dental caries and periodontal disease of the old in Hoang Mai district. The result showed that group aged from 65-74 possesses 57.3 percent, group aged or = 75 does 42.7 percent. Percentage of people who have no knowledge about dental caries and periodontitist, was very high (62.65 percent). Scale of people who brush their teeth daily was 73.7 percent and people who did not brush their teeth daily, possesses a remarkable percentage (26.3 percent). When had dental problem, only 36.3 percent of people comes to dental clinic. In conclusion, knowledge about dental caries and periodontal disease in study's sample was not good yet. Level of knowledge increases by educational degree. Percentage of people who did not brush their teeth daily, was 26.3 percent. Percentage of people brush their teeth 1 time per day was 80.5 percent, that people take 1 minute to brush was 75.6 percent. Dental attitude and practice were still bad.