Objective: The purpose of the present study was to examine how children’s transition to adulthood might be related to their parents’ marital satisfaction and relationship satisfaction with children. Specifically, we investigated if the numbers of children who (1) graduated from 4-year college, (2) were employed, (3) were married, (4) moved out of parental homes and lived independently, and (5) had at least one child might be associated with better marital satisfaction and higher relationship satisfaction with children among midlife and older parents. We also evaluated if the associations might differ by gender of the children (sons vs. daughters) as well as by their gender and birth order (first-born son, later-born son, first-born daughter, later-born daughter). Method: The analytic sample was drawn from the 2006 Korean Longitudinal Study of Ageing. The sample consisted of 1,905 parents whose children were aged between 25 and 35. For analysis, regression models with robust standard errors were estimated using Stata. Results: Results suggest that sons’ (especially first-born sons’) transition to adulthood exerted more consistent impacts on parents. More specifically, first-born sons’ completion of higher education, marriage, and independent living arrangement were associated with either higher levels of parental marital satisfaction or relationship satisfaction with children. With regard to later-born sons, their completion of college education was linked to higher levels of parental marital satisfaction and relationship satisfaction with children. Conclusion: Korean parents appear to place greater importance on first-born sons’ successful transition to adulthood compared to those of other children. Overall, however, transition to adulthood may have limited influence on Korean parents.