Objectives: This study aimed to assess the socio-economic inequalities in the self-rated oral health status in the study group of South Koreans, as associated with other factors (health behaviors factors, psychological factors, and oral health status) on the social gradients in the self-rated oral health status. Methods: The cross-sectional data was from the Forth Korea National Health & Nutrition Examination Survey. Subjects were 18,886 people over the age of 6 years who participated in the health interview, dental examination, and dietary survey. They were divided into four groups according to their life course: children (6-11 years), adolescents (12-18 years), adults (19-64 years), and the elderly (65 years and older). The income and education level brackets were selected as measures of socio-economic position (SEP). The complex samples logistic regression models were used to analyze the data. To assess the association of the other factors, additional models (which adjusted for the gender, age, and each of the other factors) were compared to the initial model (which adjusted for the gender and age only). Results: We found that there were socio-economic differences in the self-rated oral health status at all stages of life, and that the differences were up sharply for the vulnerable social groups. Dental care utilization factors and the oral health status mainly affected the socio-economic inequalities of the poor self-rated oral health status group at all stages of life. Socio-eoconomic differences remained statistically significant in the models that controlled for all related factors except the models of household income in adults. Conclusions: There were socio-economic differences in the poor self-rated oral health status at all stages of life. But it is difficult to definitely confirm the pathway of socio-economic inequalities in the selfrated oral health status, because of the limitations of the cross sectional study and the use of restricted variables in this survey. Therefore more extensive longitudinal research is required to better address the pathways that explain the socio-economic inequalities in the self-rated oral health status throughout the life courses in the Republic of Korea.