The Welsh Assembly Government is being urged to provide more cash to one of Wales' biggest hospitals in order to prevent cutbacks in services.
The hospital treats patients from a wide area of north Wales
Glan Clwyd Hospital in Denbighshire, faces an £8m shortfall and managers are to meet assembly officials on Friday.
They say emergency care and waiting times remain their top priorities.
Meanwhile Wales' biggest trust - Cardiff and Vale - has revealed it too faces a deficit, of £13.9m, but says patients will be unaffected.
Glan Clwyd hospital managed to break even last year but members of its trust board have been told it is becoming more difficult to operate within the budget.
Managers have described the situation as "serious" and warned that "painful" changes were necessary.
While he said he was confident the hospital would get through "these difficult times" and continue to provide first class health care, Chief Executive Gren Kershaw warned: "The problem is extremely serious and we must move quickly to prevent the situation deteriorating," said Mr Kershaw.
"All our staff realise that we have to live within our means, and some of the changes we make may be painful"
Unions are warning that one measure being considered is a vacancies freeze which would hit patient care.
Efficiency savings of more than £4m are already planned at Glan Clwyd Hospital this year.
That will mean fewer staff and changing the way services are delivered but managers say there remains a shortfall of eight million pounds.
Now, North Wales Assembly member Mark Isherwood is urging the assembly to provide more money, saying that Glan Clwyd is an efficient hospital and warning that having to make further savings will cut into the bone of the services it currently provides.
While hospital managers are meeting to discus the situation with assembly health officials at a meeting in Mold ahead of the weekend, it is not expected the issue will be resolved on Friday.
The hospital - which is marking its 25th anniversary this month - caters for patients from across a wide area of north Wales.
The most recent figures show that over a year it treated more than 36,000 inpatient cases and almost 51,000 people in accident and emergency.
In south Wales, Cardiff and Vale NHS Trust says it has a cost reduction programme in place because of a 'substantial' £13.9m shortfall for 2005-06.
It says the two biggest savings are in cutting the use of agency staff and reducing non-essential purchases. The trust says these savings would not affect patient care.