Can Koreans marry someone with the same last name?

Yes. Two Kims can marry, and so can two Gimhae Kims — but that has only been true since 1997. For five centuries Korea enforced one of the strictest marriage prohibitions in the world: no marriage between people who shared both a surname and a bon-gwan (ancestral clan seat), however distant the relationship. This page explains the old rule, the court case that ended it, what is still illegal today, and the related question of why Korean wives keep their own surname.

The old rule: dongseong-dongbon

The prohibition was called 동성동본 금혼 (dongseong-dongbon geumhon) — “same surname, same clan seat, marriage forbidden”. Two people were barred from marrying if they shared a surname and a bon-gwan, because that made them members of the same patrilineal clan and therefore, in Confucian terms, relatives, even if their common ancestor lived a thousand years ago and 30 generations back. A Gimhae Kim could not marry another Gimhae Kim. A Gimhae Kim could marry a Gyeongju Kim without difficulty, because the two clans have different founders.

The rule came from Chinese Confucian ritual codes and was written into Joseon law in the 15th century. It survived the fall of the dynasty and was carried into the Republic of Korea’s Civil Code in 1958 as Article 809, which stated that “a marriage may not be allowed between blood relatives having the same surname and the same origin of surname”.

How many couples it affected

Because Korean surnames are so concentrated, the ban caught an enormous number of ordinary couples. The Gimhae Kim clan alone has more than four million members — nearly one Korean in twelve — so two random Koreans had a meaningful chance of being dongseong-dongbon. By the 1990s an estimated 200,000 couples were living together unable to register their marriage, with children who could not be registered as legitimate. The government had to pass temporary amnesty laws in 1978, 1988 and 1996 that opened one-year windows for these couples to register.

The 1997 Constitutional Court decision

In July 1997 the Constitutional Court ruled that Article 809 was incompatible with the constitution’s guarantees of human dignity, the right to pursue happiness and equality, and with the principle that marriage is founded on individual choice. The court observed that a ban based on a shared surname rather than actual blood relationship had no rational connection to preventing consanguineous marriage. The article lost effect from 1999, and the National Assembly formally replaced it in the 2005 revision of the Civil Code, effective 2008.

What is still prohibited

Korea now uses a degree-of-kinship rule instead of a surname rule. Under the revised Article 809, marriage is prohibited between:

• Blood relatives within the eighth degree — that is, up to third cousins, on either the father’s or the mother’s side.
• Certain in-laws within the sixth degree, and former in-laws within the fourth.
• Adoptive relatives within the sixth degree.

Eighth-degree kinship is still wider than most Western countries (which typically stop at first cousins), but it is based on an actual family tree, not on a name. Two Gimhae Kims who are not related within eight degrees can marry freely, and many do.

Do Korean women take their husband’s surname?

No, and they never have. A Korean woman keeps her birth surname for life; there is no legal or social mechanism for changing it on marriage. Historically this reflected the same clan logic as the marriage ban — a woman remained a member of her father’s lineage and could not “become” a member of her husband’s — rather than any idea of equality. Today it is simply the norm: Kim Yu-na would still be Kim Yu-na after marrying a Park. Children take the father’s surname and bon-gwan by default; since the 2008 reform, parents can agree at the time of marriage registration to give children the mother’s surname instead, and a family court can approve a change later for the child’s welfare. Fewer than one percent of couples choose the mother’s name.

Korean names in international marriages

When a Korean marries a foreigner, Korean law still does not change the Korean spouse’s surname. Korean women married abroad sometimes adopt the husband’s surname for local documents while keeping their Korean name on their Korean passport and family register, which occasionally causes paperwork confusion. Children of a Korean father registered in Korea take his surname and bon-gwan; children of a Korean mother and foreign father can be registered under the mother’s surname since 2008.

Frequently asked questions