Police recorded 1,200 assaults between residents living at care homes between 2014 and 2016, the BBC has found.
More than one assault a day was reported in England and Wales, an investigation by File on 4 revealed.
Some care workers said they were not always given full information about who might pose a risk.
The Care Quality Commission, the health regulator in England, said it was the responsibility of care providers to protect residents from harm or abuse.
Alison Wallace Wood’s father, Allan Wallace, died less than three weeks after being assaulted at Mapleford Nursing Home in Accrington, Lancashire, in October 2015.
“They found my father on the floor in a very distressed state, bleeding from head wounds,” she said.
“It appeared that he’d been kicked in the head and the chap was wearing steel toe cap boots which nobody was aware of. He was very, very bruised, very incoherent, semi-conscious really. Bruising around the ears, around the head, on the hands. He looked a mess.”
Allan, who was 86 and had dementia, never recovered from the altercation. An inquest into his death ruled that he died from natural causes contributed to by the injuries he sustained.