Evidence on the relation of socioeconomic position (SEP) with health and illness is mounting in South Korea. Several unlinked studies and individually linked studies (longitudinal study) showed a graded inverse relationship between SEP and mortality among South Korean males and females. Based on the mortality relative ratios by occupational class reported in the published papers of South Korea and western countries, the magnitude of the socioeconomic inequality in mortality in South Korea seems to be similar to or even greater than that in western industrialized countries. A potential contribution of health related selection, health behaviors and psychosocial factors to explain this socioeconomic inequality in mortality was discussed. It was suggested that early life exposure measures would demonstrate a greater ability to explain socioeconomic inequalities in all-cause mortality than the above pathway variables in South Korea. This is based on the cause-specific structure of mortality among the South Korean population who have a relatively greater proportion of stomach cancer, hemorrhagic stroke, liver cancer and liver disease, and tuberculosis, which share early life exposures as important elements of their etiology, than western countries. However, the relative contribution of early and later life socioeconomic conditions in producing socioeconomic inequality in health may differ according to the outcome, thus remains to be investigated.