The Waikato DHB says that unless it is able to reduce the number of people coming into its emergency department, it won't be able to reach a Government target of 95% of patients being seen and dealt with within six hours.
In the latest quarterly results, Waikato rate an 88% turnaround, bottom equal of the 20 district health boards.
The Waikato board said there was an 11% increase in the past year of people at the emergency department.
Dr John Bonning said people need to think about whether their problem warrants a hospital visit or one to their GP.
Nearly 67,000 patients arrived at the emergency department last year. Group manager Mark Spittal said up to 15 extra patients were being admitted every day in the last quarter than in the previous year.
In 2012, an expected second peak of children being admitted with flu struck in November, not late winter as expected, and that affected the results from the last quarter of the year.
Mr Spittal said staff numbers are being increased in the emergency department following a world-wide recruiting drive.