The Irish Cancer Society is warning that some patients are being harassed by debt collectors for hospital fees.
The charity claims the HSE is passing outstanding payments on to private collection firms for in-patient procedures like chemotherapy.
In some cases of "excessive hardship", hospitals may waive the charge or agree instalment plans with patients.
However, arrangements are at the discretion of the hospital.
CEO of the Irish Cancer Society, Averil Power, says patients should not have to deal with the pressure of payments.
Ms Power said: "We're calling on the Government to abolish in-patient charges in the next budget, cancer patients simply don't have the money to pay €800 for chemotherapy appointments.
"Getting threatening letters from debt collecting agencies is just adding extra fear and stress at a time when people are already suffering physically and emotionally."