More than 25 per cent of patients who attended KGH’s A&E department in December had to wait for longer than four hours.
New NHS figures show 7,488 people visited A&E there in the last month of 2017.
A total of 73.4 per cent of these were admitted, transferred or discharged within the target time of four hours – meaning 1,989 had to wait longer than expected.
KGH’s chief operating officer Rebecca Brown said: “Kettering General Hospital continues to be under significant emergency care pressure.
“We saw 7,488 attendances (240 per day) in December and 2,632 of these patients required admission from A&E.
“We are seeing large numbers of older people who are very ill.
“The number of patients over 75 being admitted to hospital has gone up 21 per cent compared to the normal amount we would expect over the past four weeks.”
The target for hospitals to hit when it comes to seeing patients within four hours is 95 per cent.
In December, the national average was 85.1 per cent.
Mrs Brown added: “In December we had total hospital admissions of 3,036 patients but discharges of only 2,918 patients.
“This means that the beds on our wards are full virtually all of the time and we need more discharges to ease the pressure.
“The A&E four-hour waiting target percentage is affected by this because it means we cannot move patients out of A&E into hospital beds quickly enough.
“We would appeal to local people to support us at this busy time by not using A&E unless it is absolutely necessary and by local families ensuring that they support our discharge process as much as they can so that patients are able to go home, or into suitable community care, as soon as possible.”
Elsewhere in the county, 6,540 visits to Corby Urgent Care Centre were made in December.
A total of 99.4 per cent of patients there were seen within four hours, with 42 waiting for longer than expected.
At Northampton General Hospital, 83.2 per cent of A&E patients were seen within four hours or less.