The incident happened inside the Bainbridge Nursing and Rehabilitation Center on Bainbridge Avenue in the Norwood section around 8 p.m. Friday.
Police say officers who arrived at the 200-bed facility found the 72-year-old victim lying unconscious in his bed with a wire hanger around his neck.
The man was declared dead on the scene.
The medical examiner's office will determine the cause of death.
Earlier Friday, a 66-year-old man was arraigned on a murder charge in the beating death of his 71-year-old roommate inside a Queens nursing home. Police say that beating, on Wednesday, came after the two argued over a curtain separating the beds.