More than 130,000 hospital patients have been "boarded out" from hospital wards in the past two years, according to figures from Scottish Labour.
The practice of moving a patient from a specialist ward to a ward treating different conditions can result in them staying in hospital longer and increases the risk of infections spreading, researchers have said.
Freedom of information requests from Scottish Labour found health boards have moved more than 130,000 patients between wards.
The party said the number could be higher with Tayside and Grampian health boards not providing information.
Dundee University researchers examined boarding last year and said a reduction in bed numbers and a rise in hospital admissions had led to it becoming more common.
The Scottish Government said it is working to reduce the practice.
Scottish Labour said the figures "showed the huge strain our hospitals were under" and called for more investment in social care.
The party's public services spokeswoman Jackie Baillie said: "These figures point to huge levels of stress in our hospitals. We know that only a third of NHS staff believe they have the resources to do their jobs properly.
"This information suggests that too often there isn't enough space for patients to be treated in the appropriate ward. That is hugely concerning.
"We know from the SNP Government's own research treating patients in the wrong ward more likely to increase patient risk. Questions have to be asked of Shona Robison about what she is doing to deal with this.
"Scottish Labour would give our NHS established in the 1940s, the tools it needs to face the challenges of the 2040s.
"This starts with substantial investment in social care. Greater investment in social care would take significant pressure off of our hospitals and that starts with delivering a national care workers' guarantee on wages, terms and conditions."
A spokesman for Health Secretary Shona Robison said: "Scotland was the first among the UK nations to take a proactive approach to tackling the issue of boarding. We've investigated its causes and the effect it has on patients and are working closely with experts at the Royal College of Physicians of Edinburgh to reduce the practice.
"We recognise that peaks in demand may require use of beds flexibly at times, however we are working to ensure that NHS Boards are managing their capacity and ensuring that patients are admitted to the right beds at the right time with the right staff.
"Key elements of our work to reduce boarding include freeing up capacity and easing pressure across the system. For example, our investment of £100m over three years in reducing delayed discharge is already seeing real results with a 13% reduction in bed days lost to patients ready to go home.
"Labour should now commit to backing the Scottish Government's budget that will invest £250 million in social care and deliver a living wage for all social care staff - helping deliver integrated health and social care and see people cared for as close to home as possible."