Navratilova was diagnosed with high-altitude pulmonary edema, Dr. David Silverstein, a consultant in cardiology and internal medicine at Nairobi Hospital, said Friday.
"It is potentially dangerous when someone is at high altitude, but once brought down, recovery is quick," he added. "Martina is doing well and will continue to do well."
Navratilova was assisted down Africa's highest peak by porters and driven to the Kilimanjaro Christian Medical Centre.
She was trying to climb the mountain in Tanzania for a sports charity as part of a 27-person team. It faced heavy snows and mist since beginning trek Monday up the 19,340-foot mountain.
"I'm disappointed not to be able to complete this amazing journey," she said in a statement. "It was something that I have wanted to do for so long but it was not to be."
Navratilova told The Associated Press last weekend she has never climbed higher than 12,000 feet. She had reached nearly 14,800 feet when forced to give up, according to the charity.
The winner of 18 Grand Slam singles titles added at the time she was "petrified" of failing to reach the summit "because then the whole world will know."
Navratilova was making the climb to raise money and awareness for the Laureus Sport for Good Foundation. The rest of the team will continue the climb and should reach the summit Saturday.
For more info:
The Laureus Blog