The long-running case had been scheduled for a lengthy civil hearing to begin in the NSW Supreme Court on Monday, but the parties instead reached a last-minute agreement to settle the dispute for $25 million.

Damages had been sought for physiological and psychiatric treatment, as well as added costs of further revision surgery, medical monitoring and other losses.

The surgeries were conducted at The Cosmetic Institute's Sydney clinics at Parramatta and Bondi Junction, as well as at other facilities in the NSW capital and on the Gold Coast.

The class action argued patients were not told of the risk of harm from the firm's "One Size Fits All" procedure and staff at the clinic were negligent and breached their duty of care and consumer guarantees.

Out of the total settlement, just more than $2.8 million will be paid out to the 12 lead plaintiffs who headed up the case.

A further $10 million will be requested by law firm Turner Freeman to cover its costs of running the lawsuit and future expenses working out the amount of compensation payable to women who come forward.

The remaining $12.2 million will be split between any other affected women.

The Cosmetic Institute and its subsidiaries are now under liquidation and may not need to pay anything.

The firm's director and lead plastic surgeon, Eddy Dona, has been pursued by the class action.

He is alleged to have designed the procedure and trained 11 employees, who were also sued in the lawsuit.

Three insurers for The Cosmetic Institute have been included in the class action.

Under the proposed settlement, there have been no admissions of liability made by the liquidated medical firm or its former employees.

The court will hear objections from affected women and arguments about whether the settlement is fair and reasonable at a two-day hearing scheduled for May 13.

A judge will then decide whether to sign off on the deal.