Officers were called in to intervene after a scuffle between two elderly women in the southern suburb of Alimos on Friday left one injured.
Police who arrived at the scene were told an 81-year-old woman beat up a 95-year-old, causing her light injuries to her head and body.
An ambulance transferred the victim to the Asklipieio Hospital in Voula, while the alleged perpetrator was taken to the local police station.
A prosecutor who was informed of the incident ordered the 81-year-old to undergo a psychiatric evaluation.
It remained unclear late on Friday what led to the fight.