A man aged 31, two men in their fifties and a 62-year-old were arrested at houses in the Dungiven area.
Police also carried out a series of searches.
They said they were investigating paramilitary activity, including shootings and threats, predominantly over the past four years.
The men have been taken to Antrim police station for questioning.
It's being reported by the Derry Journal that one of the men arrested is a Sinn Fein Cllr.