A poll of more than 1,200 nurses and health care assistants found half of those working in casualty departments saw treatment being given outside of medical areas every day, because units were too full.
Dr Peter Carter, the general secretary of the Royal College of Nursing (RCN), which carried out the survey, said patients' safety was being put at risk because they could not be properly monitored – with too many left in distressing situations which compromised their privacy and dignity.
The claim of mounting pressures on the NHS comes as separate figures disclose thousands of healthy elderly and disabled people being admitted to hospital wards because home helps could not be found.
NHS records show nearly 17,000 hospital stays were "booked" by medical professionals in 2010/11 because the person's usual carer – paid or unpaid – was due to take a holiday.
In all, more than 70,000 bed days were allocated to such admissions – the equivalent of an average district hospital filling every ward with healthy patients for more than five months.
The RCN found that one in five nurses and health care assistants said patients were receiving care in corridors or other unsuitable areas every day.
The figure rose in Accident and Emergency (A&E) departments, where more than half of staff said it occurred daily, and one in five said it happened ever hour of the day.
Health service figures show the number of people attending A&E departments has risen by 60 per cent in the past decade, with a similar rise in numbers admitted to hospital as a result.
Over the same period, the total number of hospital beds has fallen by 22 per cent.
Hospital managers say the reductions in bed numbers reflects increasing efficiency, and improvements in medical treatment so patients can be discharged more quickly, but the RCN says changes have gone too far, and been financially driven.
Dr Carter said treating patients on corridors was a "high risk strategy", putting them in danger without proper monitoring or access to call bells.
Nurses also reported patients being held in ambulances, or in queues outside A&E departments, because of shortages of beds and trolleys. Nearly two in five said they saw this daily.
One in three of the 1,246 nurses polled by ICM research through the RCN website said patients were moved every day for non-clinical reasons, such as to hit hospital targets.
Almost half said patients had spent long periods on trolleys, while being cared for or awaiting care, in the past six months. The average time waiting on trolleys for treatment was estimated by nurses to be six hours 23 minutes, with some cases reported of more than 24 hours.
NHS rules say 95 per cent of patients in A&E departments should be seen within four hours of arrival, and admitted to a ward, or treated and discharged.
Under Labour, the target was 98 per cent, but the Coalition reduced this because of concerns that the threshold was distorting clinical priorities.
What nurses are saying suggests the health service is "heading back to the bad old days of the 80s and 90s when patients were left on trolleys for hours on end."
The concern must be that patients are paying the price for the Government's decision to reorganise the NHS at a time of financial challenges.