Wanda has arthritis and Winky has foot problems after years of bitter winters and tight living conditions at the Detroit Zoo.
So the zoo is granting them amnesty in a rare attempt to end their suffering.
The Asian females will be sent to a wildlife refuge this summer or early fall, making the zoo the nation's first major animal facility to give away its elephants solely on ethical grounds, according to the Humane Society of the United States.
Zoo officials are seeking to send the elephants either to a Tennessee elephant sanctuary or to the Performing Animal Welfare Society preserve in Galt, California. Both have many acres of habitat.
"People's traditional expectation of zoos is that they see lions and tigers and elephants," zoo director Ron Kagan said. "But it's also their expectation that an animal has a good life."
The zoo is widely recognized for its superior animal care. But Kagan said life in captivity has been rough for the two elephants.
In the wild, female Asian elephants typically roam 30 miles a day. They form solid social bonds with members of their herds and strongly desire physical and intellectual stimulation.
But Winky, 51, and Wanda, in her mid-40s, have lived through Michigan winters for 14 and eight years, respectively. They have experienced boredom and stress while living inside their one-acre enclosure -- 16 times larger than what the American Zoo and Aquarium Assn. requires of its members who have elephants.
Wanda takes anti-inflammatory medication for chronic arthritis in her front legs. Winky has foot problems that might be related to sleeping unnaturally in a standing position; elephants sleep on soft surfaces in the wild.
"Now we understand how much more is needed to be able to meet all the physical and psychological needs of elephants in captivity, especially in a cold climate," Kagan wrote in memorandum explaining the decision.
The memo said it would cost $30 million to $50 million and require up to 20 acres of land to provide an adequate environment for the elephants. The price was so high it was never considered.
Five U.S. zoos have closed elephant exhibits in recent years amid public pressure following animal deaths or alleged mistreatment. A small animal sanctuary in Georgia surrendered its elephants earlier this year, partly because of space and cost concerns.
But the Detroit Zoo "is the first to make a purely voluntary decision of this nature," said Wayne Pacelle, chief executive officer of the Humane Society of the United States.
"This is precedent-setting," Pacelle said.
"It will reverberate throughout the zoo community and, by extension, be an indictment of what goes on in circuses where elephants are chained 22 hours a day."