What was the name of the episode where the crew ages rapidly?

“The Deadly Years” is the Star Trek: The Original Series episode in which members of the Enterprise crew age rapidly. It is the twelfth episode of the show’s second season and first aired in 1967.

Captain Kirk, Spock, McCoy, Scotty, and Chekov are exposed to a mysterious condition while visiting Gamma Hydra IV. The disease causes their bodies to age at an extraordinary rate, producing weakness, memory loss, and eventually life-threatening deterioration. Chekov is the only principal crew member to avoid the effect because he was not present during the initial exposure.

Dr. McCoy searches for a treatment while Commodore Stocker prepares to take command, believing Kirk is no longer fit for duty. The crisis becomes especially dangerous when the Enterprise approaches the Romulan Neutral Zone and faces a possible military confrontation.

Viewers sometimes confuse this story with “Miri,” another episode involving accelerated aging. “Miri,” however, concerns children on a parallel Earth and a different disease; “The Deadly Years” focuses on the Enterprise officers themselves.