Objectives: The purpose of this survey research was to investigate the relationship among oral health State, behavior and knowledge of oral health of patients who participate in dental hygiene students voluntarily. Methods: The subject in this were patients who got a scaling at the oral hygiene practice lab in the department of dental hygiene in S university dental clinic from April 1 to May 31, 2010. For the data analysis, an SPSS WIN 11.5 program was used and its signification level was 0.05. Results: 1. For the oral health state according to sex distinction, it showed the men's 0.78 MT index was higher than women's 0.48 MT index and statistically significant difference. For FT index, women(4.72) was higher than men(3.50) and it showed statistically significant difference(p<0.05). 2. For the oral health state according to age distinction, DT index of under 20years(2.44) was higher than the others and it showed statistically significant difference(p<0.05). 3. For the oral health state according to marriage distinction, not married DT index(1.59) was higher than married DT index(2.56) and it showed statistically significant difference(p<0.05). 4. For the oral health behavior according to age distinction, 87.0% 20∼29years patients replied as I have experience of my teeth scaled and it showed statistically significant difference. 18.5% more than 30years replied as I use interdental brush and it showed statistically significant difference. 18.5% more than 30years replied as I use powered brush and it showed statistically significant difference(p<0.05). 5. For the oral health state according to oral health behavior distinction, there were significant difference that regular visit of dental clinic, experience of teeth scaled, toothbrushing, oral hygiene device(p<0.05). 6. For the oral health state according to oral health knowledge distinction, there were significant difference that toothbrushing time after each meal, appropriate toothbrushing time, toothbrushing method, dental caries foods(p<0.05). Conclusions: I suggest with the result of the study that there was a very close relationship between oral health status , behavior and knowledge of oral health. Therefore student of the dental hygiene should be encouraged to pay more attention to oral health care of the patient, and they should be well educated oral health care personnels who volunteers in practice for oral prophylaxis.