Dental and oral health needs to be considered in addition to general health, because the health of teeth and mouth can effect the overall health of the body. The purpose of this research is to know the level of knowledge about dental hygiene and the value of OHI-S in grade V students in Elementary School 3 Kerobokan. This type of research is descriptive research with survey design. This research was conducted at Elementary School 3 Kerobokan, Kuta Utara District, Badung Regency in June 2018, with 108 respondents. The results frequency of knowledge level with criterion very good 9,2%, with good criterion 45,4%, with enough criterion 26%, with criterion less 12%, and criterion failed 7,4%. The average value of the students knowledge level of 65.74 includes sufficient criteria. Frequency of OHI-S score with good criterion 59,2%, medium criterion 40,8%, and no respondent with bad OHI-S criterion. The average value of OHI-S is 1.15, including good criteria. It is advisable for health workers to plan extension programs with methods that are easily understood by students and for students to control dental and oral health to health services every 6 months.