Family life culture embodies the ways of thinking and behaving among family members in everyday lives. With a noticeable growth of multicultural families since 2000, there has been an inflow of other culture into the existing Korean family life culture. This new phenomenon signals a potential transformation of the family life culture in Korean society. To forecast such changes, we compared the family life culture of Korean-Vietnamese multicultural families (as reported by 104 Korean husbands and their Vietnamese wives) with that of mainstream Korean families (as reported by 108 Korean married men and 92 Korean married women) by comparing family ritual practices and family values. We also sought to identify whether two cultures in Korean-Vietnamese multicultural families harmoniously coexist or clash by examining differences within couples. Results showed that Korean married men and Korean husbands of Vietnamese women were very similar in terms of family ritual practices and family values. Differences emerged between Korean husbands and their Vietnamese wives. Specifically, Korean husbands endorsed more traditional gender role beliefs while their family values were less patriarchal compared to their wives. Results suggest that more flexible gender role beliefs reported by Vietnamese wives may be a source of conflict in Korean-Vietnamese multicultural families. At the same time, it may be a driving force of change in their existing family life culture. It will be worthwhile to pay attention in future research to whether and how patriarchal values and flexible gender role beliefs would continue to coexist or modify each other.