The number of people waiting longer than nine weeks for a first hospital appointment has jumped by more than 6,000% in just two years.
According to figures released by the Department of Health, almost 32,000 people waited longer than nine weeks for a first outpatient appointment at the end of March this year - compared to just 488 people in March 2009.
Under government targets, no one should wait longer than nine weeks for a first outpatient appointment.
The Chartered Society of Physiotherapy (CSP) in Northern Ireland described the situation as "totally unacceptable".
Tom Sullivan, CSP policy officer, said: "Waiting time figures show that the number of patients waiting longer than the nine-week target for a first outpatient appointment is 270% higher than the same figures published a year ago.
"The number of patients waiting longer than 13 weeks for their first outpatient appointment has increased by over 400% in the same period.
"Frontline staff are struggling to meet their targets as a direct result of the number of unfilled vacancies imposed across all the trusts.
"These vacancy controls have left some physiotherapy departments chronically understaffed and are clearly having an impact on patients' ability to access the care and treatment that they need and deserve."
Dr Brian Patterson from the British Medical Association said more needs to be done to improve the patient experience here.
"There has been an improvement compared to the previous quarter but not when you look back to the same period in the past two years," he said. "We need to ask how this happened and whether the reduction in waiting times is sustainable."
Health Minister Edwin Poots said he wants to examine the issue.
"I want to limit needless admissions - this will include good intermediate care, rehabilitation, community packages and bolstering multi-disciplinary community teams for chronic conditions such as heart failure, diabetes and chest disease," he added.
The 2010/11 government target for outpatient waiting times states that by March 31 2011, no patient should wait longer than nine weeks for a first outpatient appointment. The number of people waiting for a first outpatient appointment at the end of March 2011 was 106,227. Of these, 31,909 (30%) patients waited more than nine weeks for a first outpatient appointment.