Some public hospitals charge twice as much as others for similar procedures to similar patients, a new report by the health monitoring agency says.

Surgical procedures could cost twice as much depending on the public hospital you attend.

That is the finding of a new report by the independent agency monitoring the health system after it studied costs at more than 80 of the nation's largest public hospitals.

The National Health Performance Authority discovered procedures in some hospitals cost almost twice as much as the exact same procedure in another comparable hospital.

Among large metropolitan hospitals, costs varied from $3200 to $6400, while among major regional hospitals, costs ranged from $3600 to $5300.

For example, a patient needing their appendix removed could be charged either $4600 or $10,000 depending on which major metropolitan hospital they attended.

Victoria topped the nation with the most low-cost hospitals, while the ACT had two of the most expensive hospitals.

The authority says the results could be used by hospitals to find efficiencies in their costs and procedures.

CHARGES
* Knee replacement: From $10,600 to $29,300 in metro hospitals; or from $10,700 to $22,600 in regional hospitals
* Vaginal birth: From $2200 to $6500 among metros; from $3100 to $7500 among regionals
* Appendix removal: From $4600 to $10,100 among metros; or from $4300 to $9300 among regionals

LOWEST-COST METRO HOSPITALS - ALL IN VICTORIA
* Maroondah Hospital (Ringwood East)
* Sunshine Hospital
* The Northern Hospital (Epping)
* Dandenong Hospital
* Royal Melbourne Hospital (Parkville)

HIGHEST COSTS
* Canberra Hospital (ACT)
* Sir Charles Gairdner Hospital (WA)
* Calvary Public Hospital (ACT)
* Logan Hospital (Queensland)