The purpose of this research was to assess the oral-health related quality of life among the institutionalized elderly and to identify its relevant factors. Cognitively coherent residents in two institutions in Taipei were recruited into the study using a convenient sampling technique and cross-sectional data was collected. A total of 224 subjects participated in this study. Demographic characteristics, chronic conditions, physical function, cognitive function, and geriatric oral- health related quality of life assessment (Geriatric Oral Health Assessment Index；GOHAI) were collected through face-to-face interviews, while information regarding dentition status, periodontal status, occlusion status and prosthetic status were collected through clinical examination. Results showed that the average GOHAI score was 50.7 out of 100, with 44.2% of subjects scored less than 50. Multivariate linear regression showed that, after controlling for demographic characteristics, the Eichner index, kinds of eating food and functional dependency are significant predictors of GOHAI scores. The model explained 17.5% of the total variance. Examining the three domains (physiological, social, and discomfort) of GOHAI individually, results showed that the Eichner index was highly correlated with the physiological domain of GOHAI, but not with the social or discomfort domains. The model explained 30.2% of the variance in the physiological domain. Eichner index is the most important predictor of oral-health related quality of life among the institutionalized elderly. Dental health policy should emphasize on using an objective and self-reported assessment for screening subjects in need of early intervention.