Reynolds, 84, was at her son Todd Fisher's home in Beverly Hills, California, discussing funeral arrangements for herStar Wars actress daughter Carrie Fisher, who died on Tuesday, when she fell ill, TMZ reported.
She was rushed to hospital, but her son confirmed she had died a short time ago, AP and Variety has reported.
Emergency services were called shortly after 1 pm (local time), said TMZ, which reported that she had a possible stroke.
Fisher died in hospital yesterday after having a heart attack on a flight last Friday.
