The city council formed the sister city relationships with Saitama City in Japan, Wuxi in China and Sacramento in the United States in the 1980s.
In the past two years the council has spent $1797 on its contact with Saitama - hosting three lunches for visiting children as part of the school exchange programme - and $923 on a ceremony in June where the city was presented with a 120-year-old children's shrine.
Hosting delegations from Wuxi has cost $882.
Ms Hardaker said Hamilton schools had developed a good student exchange programme with Saitama, and some businesses in the city, including educational institutes, had established links with Wuxi.
She understood, however, that Hamilton had had "little if any communication" with Sacramento since the link was formed in 1989.
"The world has changed since then and the relationships that the city now have are about an economic and business relationship so I'm interested to explore that and maximise that," she said.
"I think that relates to the kind of business that's done in our city through international relationships and who those are with. What countries, and mostly they are with Asia, and how the city can assist in that way."
Delegations from other international cities have visited Hamilton, and last year Ms Hardaker and her husband, Steven Perdia, visited Chengdu in China - at no expense to the city - to drum up business.
Ms Hardaker said the city had not incurred any expenses sending staff or delegations to sister cities during her time as mayor.
She had not visited a sister city and said she had no intention of visiting any of the cities this term.
But the current policy required the mayor to lead a delegation to a sister city at least once during each three-year term, and this would be raised in the review.
Hamilton City councillor Angela O'Leary questioned the costs and purpose of the sister city relationships.
"We can learn from other cities and towns in New Zealand just as easily," she said.
