North Korean leader Kim Jong-il has taken his former private secretary as his "new wife", according to a report by South Korea's Yonhap news agency.
Kim Ok is said to have accompanied Kim Jong-il to China in January
Mr Kim is now living with Kim Ok, who is "virtually North Korea's first lady", an official told Yonhap.
Mr Kim's marital status has never been confirmed, but there are thought to have been three women in the past who were treated as wives.
The most recent, Ko Young-hee, died of cancer about two years ago.
Kim Ok served as the North Korean leader's private secretary since the early 1980s, another official told Yonhap.
She is said to have accompanied him on several of his inspection tours to military and industrial facilities, and also to have travelled with him to China in January 2006.
"I heard she is very wise and clever," the official said.
It is not clear what impact a new wife could have on the issue of who succeeds the North Korean ruler. Kim Jong-il succeeded his father, Kim Il-sung, and analysts expect a hereditary succession.
Kim Jong-il lived with three women in the past, and has fathered several children
Eldest son Kim Jong-nam disgraced himself in Japan, but may be back in favour
Others think a younger boy, Kim Jong-chul, is designated successor
Mr Kim has at least three sons - one from his relationship with Sung Hae-rim and two from his relationship with Japanese-born Ko Young-hee.
There has been considerable speculation about internal conflict between factions backing different sons for the succession.
Eldest son Kim Jong-nam was presumed to be the likely candidate, until he fell from favour after trying to enter Japan using a false passport.
Kim Jong-chul, Mr Kim's eldest son by Ko Yong-hee, is now thought by some to be the leading candidate.
It is not known whether Mr Kim and Kim Ok have any children, the agency said.
But the emergence of a new woman in the life of Kim Jong-il could add another factor to the already complicated question of who will succeed him.