An ambulance took over an hour to arrive at a life-threatening emergency calls almost 300 times in the space of six months.
According to freedom of information figures, two of the response times were over two hours.
The target is for an ambulance to arrive at a life-threatening emergency within 18 minutes and 59 seconds or less.
But for non-heart related calls, called Delta, this was reached in only 54 per cent of cases between July and December of last year.
New HSE figures show 282 times it took an ambulance over an hour to arrive at a Delta call during this period.
The longest was nearly 2 hours and 32 minutes, to a call in Co Cork.
Rural counties like Donegal, Kerry, Wexford, Galway, Monaghan, Clare and Mayo all had response times of over 1 hour and 38 minutes.
The National Ambulance Service says the response times of over an hour represent less than 1 per cent of the overall number of Delta calls during this period.
