The 52-year-old actress is seeking treatment at the Cirque Lodge, where actresses Kirsten Dunst and Lindsay Lohan have both spent time in recent years.
Griffith's representative Robin Baum tells Star magazine, "She is there to reinforce her commitment to stay healthy. This is part of a routine plan that was designed between her and her doctors years ago."
Sources tell the tabloid that the star, who is married to Spanish actor Antonio Banderas, turned to rehab after losing her longtime battle with alcohol.
An insider is quoted saying, "She's working with the counsellors on getting control of her demons. The reason Melanie checked in was her husband was demanding that she get clean and sober."
Another source tells the Star, "Melanie's struggling right now, but Antonio has been checking in on her as much as he is allowed, making sure she gets back on her feet."
Griffith battled drink and drugs in the 1970s and 80s, and spent time in rehab in 1998 and again in 2000 in an effort to kick an addiction to prescription painkillers.