Cece Yorke, a rep for the actress, tells ET, "Catherine has proactively checked into a health care facility. Previously Catherine has said that she is committed to periodic care in order to manage her health in an optimum manner."
Bipolar II is a milder form of the disorder known to cause mood swings and erratic behavior.
Zeta-Jones first announced her diagnosis in 2011, undergoing treatment at Silver Hill Hospital in Connecticut. At the time, Zeta-Jones' rep told ET that the Chicago star made the decision to enter treatment "after dealing with the stress of the past year."
The 43-year-old Oscar winner can next be seen in Red 2 alongside Bruce Willis, Helen Mirren, Anthony Hopkins and John Malkovich. The action sequel opens July 19.