The men, from Lac La Croix, are seeking unspecified financial damages from the federal government, a Catholic diocese in Thunder Bay, and the order of Les Oblats de Marie Immaculee du Manitoba, along with a priest who lived and worked on the reserve in the 1960s.
The six men allege the assaults took place in the priest's home, in a schoolhouse and in a hotel.
They say they felt powerless to speak out because of the priest's position of power in their small community.
The priest died in 1986.
The diocese of Thunder Bay says it has not been notified of any lawsuit.
Lac La Croix is located along the Ontario-Minnesota border, approximately 200 kilometres northwest of Thunder Bay.