Catherine Zeta Jones and Michael Douglas are "taking some time apart" to "work on their marriage", according to a statement released by her publicist.
The Welsh actress married US actor Michael 13 years ago and the couple have two children together.
A spokeswoman for the star said: "Catherine and Michael are taking some time apart to evaluate and work on their marriage. There will be no further comment."
Catherine, 43, shot to fame in Britain in the early 1990s playing fresh-faced Mariette Larkin in the television adaptation of HE Bates' The Darling Buds Of May before making her breakthrough in Hollywood as Elena Montero in 1998's The Mask Of Zorro.
The star has spoken openly in the past about her struggle with type two bipolar disorder and checked into a facility for further treatment earlier this year.
She has previously said of the illness: ''This is a disorder that affects millions of people and I am one of them. If my revelation of having bipolar II has encouraged one person to seek help, then it is worth it.
''There is no need to suffer silently and there is no shame in seeking help.''
Michael, the son of Hollywood star Kirk, also hit the headlines this year after he said his battle against throat cancer was caused by performing oral sex.
The 68-year-old claimed his stage-four cancer was contracted through the human papillomavirus (HPV), a sexually transmitted disease.