Barbara Sinatra, the wife of the late Frank Sinatra, died on Tuesday morning at her home in Rancho Mirage, California. She was 90.
A family spokesman tells ET that Barbara -- who was nicknamed "Lady Blue Eyes" -- died of natural causes and was comfortably surrounded by family and friends at her home. Funerals arrangements are being made and will be announced in a few days.
While her husband is known for his contributions to music and entertainment, Barbara's legacy lies at the Barbara Sinatra Children's Center at Eisenhower Medical Center, which helps abused children.
"Barbara was an avid and tireless fundraiser and child advocate, and, as the Center's Founder and Chairwoman of the Board of Directors, intimately involved in the organization's operations," reads a statement about her humanitarian work. "Through Barbara Sinatra's efforts, more than 20,000 children through age 18 have received beneficial therapy at the Barbara Sinatra Center for Abused Children, making it possible for them to cope with traumas associated with abuse."
Frank and Barbara Sinatra married in 1976 and were together until his death in 1998. Barbara is survived by her only child, Robert Marx, his wife, Hillary Roberts, and her granddaughter, Carina Blakeley Marx.
"She died comfortably surrounded by family and friends at her home," John Thoresen, director at the children's center, told ET.
The family asks that any memorial gifts be directed to Barbara Sinatra Center for Abused Children.