Etta James — famous for her incredible rendition of "At Last" — is "terminally ill" … so says her live-in doctor … who is now asking fans to pray for the 73-year-old singer.

According to the doctor, Etta's chronic leukemia was declared incurable two weeks ago.

Etta — whose health has been on a rapid decline the last few years — was hospitalized in May over a life-threatening blood infection. Months before, the singer was diagnosed with both dementia and leukemia.

At 24hourhiphop.com, our thought and prayers go out to Etta James and her family.