One in four Royal Stoke A&E patients were left waiting more than 4 hours in September.
Figures released today show 14,587 people attended the department last month, and 74.6% were seen within that time.
However, in August it was 86.6% for 15,000 attendances.
The government pledge is that at least 95% of all patients should be seen within 4 hours.
In September a total of 20,773 patients turned up to emergency and minor injury units under the University Hospitals of North Midlands Trust, which also runs Stafford's County Hospital.
82% were seen within the target time, down from 91% the previous month when 21,181 people attended them.
According to the new figures, no one had to wait more than 12 hours to be seen in the last two months.
Paula Clark, Chief Executive, said: “Nationally A&E attendances are increasing and this has meant the NHS hasn’t achieved the target for the past four years.
“UHNM is no different to other NHS providers in this respect, however, since March 2018 A&E performance has seen a marked improvement with over 90% of our patients being seen within four hours in August 2018.
“However, the period approaching winter is more challenging, and this is reflected in the September figures.
“We would like to assure the public we are consistently working towards winter 2018/2019 by increasing the number of hospital beds, including the £8.8m construction of two new wards.
“I would like to reiterate our thanks to patients and their relatives for their understanding and support, and our staff for their efforts to make patients as comfortable as possible when we were at our busiest.”