The former "Grey's Anatomy" star, 50, and his make-up artist spouse split last January, with Jillian filing for divorce citing irreconcilable differences, reported People magazine.
Legal papers at the time stated that Jillian, who married Dempsey in July 1999, was seeking joint custody of their 12-year-old daughter, Tallulah Fyfe, and seven-year-old twin sons, Sullivan Patrick and Darby Galen.
But now it has been claimed that the estranged couple have decided to give their relationship another go.
""For the past year, Patrick and Jillian have been working on getting to where they are right now. They are not dating anyone else, and only each other," a source said.