More than a fifth of NHS finance directors believe patient care will get worse over the next year, according to a new report.
Concerns centre around growing waiting times, patients' ability to access services and potential cuts to the range of services the NHS will be able to offer.
The report, from the Healthcare Financial Management Association (HFMA), included the views or around 200 finance directors in England.
It found that, overall, finance directors are more pessimistic about the quality of patient care in 2016/17 than they were in 2015/16.
Some 21% of clinical commissioning group (CCG) chief finance officers and 23% of NHS trust finance directors said the quality of patient services will deteriorate throughout 2016/17.
And a third working for NHS trusts said the quality will decline even further in 2017/18.
Meanwhile, 15% of CCG finance officers and 20% of trust finance directors think quality will improve over the next year, while around two-thirds of those in CCGs and over half of those in trusts think it will stay the same.
The report also found that 49% of finance directors in CCGs are forecasting a worse financial position at the end of 2016/17 than in the previous year.
And 67% of CCG finance officers and 48% of trust finance directors reported a "high degree of risk" associated with achieving their organisation's 2016/17 financial plan. Just 3% said there was a low risk.
The main reasons for the risk are a failure to meet planned cost savings, the high spends on agency staff to fill gaps in rotas and the impact of social care cuts, which have been widely blamed as one of the main reasons healthy people are unable to leave hospital following treatment.
Increasing demand for services was also highlighted.
Figures published in May showed NHS trusts recording the biggest ever deficit in the history of the health service, prompting fears about the future of patient care.
Data showed NHS trusts ended the last financial year a record £2.45 billion in deficit, lower than the £2.8 billion which had been predicted, but almost three times bigger than the previous year.
Overall, 65% of the 240 trusts were in deficit with nearly all hospitals ending the year in the red.
The NHS also continues to struggle to hit key targets, including the four-hour A&E waiting times target and the highest ever number of patients being delayed leaving hospital.
Paul Briddock, director of policy at HFMA, commented: "The scale of the NHS deficit continues to reach unparalleled levels, and it is unlikely the provider position will be in balance at the end of 2016/17, as originally planned.
"Fears around the impact the current financial turmoil in the NHS could have on quality are also a real cause for concern and we may start to see more of these predictions come true in the year ahead.
"To avoid this, there is a need for NHS organisations to work together to address these financial and operational pressures by the efficient redesign of services and to put an end to the shifting of financial problems between sectors."
A Department of Health spokesman said: "As this report shows, the majority of finance directors think that NHS care will either improve further or continue to be of the same world-leading standard it is now.
"We are investing an extra £10 billion a year by 2020 so the NHS can introduce its own plan for the future - by clamping down on rip off staffing agencies and investing in prevention and community health services to relieve pressure on hospitals."