The three men, all in their 50s, were taken to hospital after an incident in Woodside Road, Glenrothes at about 1am yesterday.
One of the victims, aged 50, is in a critical condition in the Western General Hospital in Edinburgh, Police Scotland said.
The other two men were taken to the Victoria Hospital in Fife for emergency treatment.
Police are appealing for any witnesses to the disturbance near Dovecote Park to come forward.
Detective Inspector Colin Robson said: "We're carrying out door-to-door inquiries around the area to try to find out more information from local residents, but I'd like to further this by appealing directly to the wider public for their assistance."