Load up your myki cards with plenty of credit, Victoria.

The growing pot of money stored in myki accounts helped earn Public Transport Victoria a cool $4 million in interest last financial year, as the public's collective myki bank account balance grew from $65.6 million to $80.9 million.

Public Transport Users Association spokesman Daniel Bowen said the price rise was 'disappointing'. Credit:Steve Lightfoot

That money went back into the public transport system, which cost $4.2 billion to run in 2014-15, PTV's annual report reveals.

With most public transport expenditure drawing on the public purse, the interest earned from myki accounts was a small but important revenue stream that could add tangible benefit for passengers, without drawing from taxpayer funds, Public Transport Users Association president Tony Morton said.