Objectives : This research aims to analyze the relationship between the state of mental illness and oral health management of mental patients in mental health care institutions. Methods : The data were randomly selected from 474 patients in mental health care institutions. and analyzed by SPSS WIN 12.0 program. Results : Schizophrenia accounted for 79.5%(337 patients) ; alcohol dependency, 5.3%(25 patients) ; mental retardation, 2.7%(13 patients) ; mental development disorder, 3.0%(14 patients) ; mental delusion and dementia, 7.6%(36 patients). Those who were in 40s had the highest dental caries of 3.95 and the highest remaining teeth of 26.76 were shown in the 20s. The correlation between remaining teeth and mental retardation was the highest, measuring 22.38(p<.05). Those who were in 70s had the serious periodontal condition that accounted for 41.3%(12 patients)(p<.05). The correlation coefficient for all factors-dental caries, remaining teeth, need for scaling, and periodontal condition-between mental illness condition and oral health were all positive(p <.05). The regression analysis resulted in the formula Y(mental health condition)=2.999+0.166(dental aries)-0.028(remaining teeth). Conclusions : Those who had mental illness had very poor and serious dental caries and periodontal diseases, so it is necessary to manage the dental health care for the mentally ill patients.