A rise in numbers going into Russells Hall in Dudley has resulted in patients being treated in corridors because of a shortage of staff and beds.
This has led to concerns over "patient safety and staff wellbeing issues" being escalated to the board of directors at the trust which runs the hospital.
The problems at Russells Hall come amid a national NHS crisis, with current A&E waiting times the worst on record.
The plight of patients being treated in corridors at the Dudley hospital was revealed in a new trust board report.
It has led to questions from within the Dudley Group NHS Trust about whether the hospital was prepared for the level of demand over recent weeks.
Chief nurse Mary Sexton told a recent board meeting that the trust "did have a workforce profile and staffed to those numbers but didn’t expect to have the level of demand experienced and this had resulted in corridor care" in response to concerns about planning for patient numbers.
Mike Wood, Conservative MP for Dudley South, said: "Most people would agree that it is completely unacceptable for very ill patients to be waiting in corridors waiting to be admitted.
"New improvements to the emergency department at Russells Hall should help but there clearly needs to be action much more quickly than that. The hospital needs to look at how it can move patients onto the wards more quickly."
Karen Kelly, chief operating officer at the Dudley Group, said the hospital was experiencing "unprecedented demand".
She said: "All patients are triaged and clinically assessed on arrival and will have a plan of care in place, however they may then wait in order of clinical need for space in the main department or on a ward.
"We would never want patients to have to wait for longer than they would reasonably expect, but due to the number of patients that may attend our emergency department there have been times when they may have to wait in the corridor. In these circumstances we ensure that there are staff in the corridor to ensure that our patients remain safe.
"We apologise to anyone who has experienced a long wait. However, we will always see patients in order of clinical need."
It is the latest indication of the strain being placed on Black Country hospitals. Almost all beds were full at Sandwell and Birmingham City hospitals in the run-up to Christmas.
Health Secretary Matt Hancock suggested last week that the national A&E target of having 95 per cent of patients seen within four hours could be scrapped.
Dudley Group combines its A&E performance with that of its urgent care centre, pushing up the overall figure which was 79 per cent in November.