Update 9.09pm: The HSE has offered to meet with the Irish Cancer Society after it highlighted the major costs of hospital car parks.
The executive says parking charges are invested back into services, and they ensure the availability of parking spaces.
However, it says it has no policy or guidelines on the issue.
Cancer patients are spending up to €63 a week on parking charges at Irish hospitals according to the Irish Cancer Society.
The charity is calling on the HSE to make parking free of charge for patients attending clinics.
The Society found that a four hour stay in Tallaght Hospital in Dublin costs €10 -more than double the price shoppers will pay in the Square Shopping Centre, just two minutes' drive away.
Last year Irish hospitals raised €16m in parking charges and the Cancer Society says the cost is putting an unnecessary strain on cancer patients and their families.
Donal Buggy, Head of Services and Advocacy at the Irish Cancer Society said: "People undergoing treatment are facing real hardship in having to deal with additional costs and large drops in income, and high car parking charges only add to this.
"We have proposed a set of guidelines for hospitals to the HSE, that, if put in place, would make a big difference to cancer patients."