Over 17,000 patients were waiting for a first hospital consultation at Letterkenny University Hospital at the end of January.
Figures from the National Treatment Purchase Fund also reveal that over 2,000 people were awaiting inpatient or day case treatment.
17,757 patients were waiting for a hospital outpatient consultation as of the end of last month, up slightly from the previous month and up 11.8% compared to the number of patients waiting in January 2019.
Over 3,830 patients are waiting over a year and a half for an outpatient appointment.
Figures also show there were 2,032 patients awaiting inpatient or day case treatment, up from 1,994 during the same period last year.
Nationally, over 556,000 patients were waiting for a first hospital outpatient consultation at the end of January and more than 67,000 were left waiting for inpatient or day case treatment.