The All-Ireland AIB League structure will continue with three division of 16 teams for the next two seasons.
Following a special meeting of the Irish Rugby Football Union on Thursday, it was agreed not to tamper with the present set-up.
A statement said that the next review of the AIB League structures will take place after a minimum of two seasons.
The decision was taken following a widespread consultation and review process.
"This review process included the views of all of the constituent clubs participating in the competition and the IRFU believes that this structure is in the best interests of Irish rugby at this time," the statement said.