The Otago and Southland District Health Boards are considering a merger that would save them hundreds of thousands of dollars a year.
The boards have developed an increasingly collaborative relationship in recent years, and have a single chief executive, Brian Rousseau.
The DHBs also share some services, including laboratory testing.
Public consultation on the merger proposal, which has been discussed for several years, begins this week.
Southland DHB chairman Paul Menzies and Otago chair Errol Miller say they are refraining from offering their views on the proposal until after the consultation period.
However, both say the boards have each saved millions of dollars from services amalgamated to date.