Her husband Frederic Prinz von Anhalt said she's running a high fever, has fluid in her lungs and an infection in her recently amputated leg.
"The doctor told me her leg is infected again. They have to treat it right now. Hopefully they are going to get her stabilized in a few hours," von Anhalt said.
Her husband said she does not recognize anyone, and added that Gabor had apparently had a stroke during or after last month's surgery.
Gabor, who turns 94 on Sunday, has been in and out of the hospital since she fell and broke her hip in July. Doctors amputated part of her right leg on Jan. 14 because of an infection.
Gabor had a priest read her last rites in August.
The Associated Press contributed to this story.