Nearly two-thirds of community nurses say they are unable to give a satisfactory service because of workloads, while half say they cannot fit extra visits to meet patients' needs into their normal working day.
The Royal College of Nursing Scotland collected the findings and warned there were insufficient resources to cope with Scottish community patient needs.
There are already signs hospitals are struggling to cope with the growing number of elderly patients. The Scottish Government's plan as the number of pensioners grow is to increasingly look after people in their own homes and prevent them from needing a ward bed.
Community nurses, whose work includes changing dressings, ensuring people take medication, and supporting families, play a key role in this strategy.
However, the RCN Scotland survey of 247 community nurses based in health boards across the country raises concern about the capacity to cope with patient number surges.
It found 70%, or 174 nurses, were not confident their community nursing service would manage if asked to take on more work from hospitals.
RCN Scotland associate director Norman Provan said: "Community nurses are having to deal with bigger case loads because our population is ageing and many patients have increasingly complex needs.
"Our members tell us they have not seen appropriate increases in the workforce to help them deal with the greater pressures that they are under."
Almost 90% of the nurses who took part in the survey said their caseload had increased in the past year, and 92% said the needs of those they looked after had become more complex.
RCN Scotland said many nurses also said with the limited number of staff and growing number of patients, they were unable to take care of other necessary duties such as paperwork and emails.
The Herald is running a NHS Time for Action campaign, highlighting evidence that hospital and care services are under increasing pressure.
A Scottish Government spokeswoman said: "More people are being treated in the community and hospital stays are shorter than ever, so the shape and size of the NHS workforce is changing.
"It is vital that changes continue to be led by in-depth and rigorous planning so we can make sure that the right numbers of the right staff group are working in the right place.
"That is why we have introduced mandatory workforce planning tools to help ensure we have the right mix and number of staff working in our hospitals and communities across Scotland."