The Palmerston North Rescue Helicopter has been called to two incidents involving quad bikes in two days.
The first incident occurred at Tangimoana Beach on Monday evening when a 13-year-old girl came off her quad bike after hitting a large piece of driftwood.
A hospital spokeswoman said the teen was currently in Palmerston North Hospital's intensive care unit, in a stable condition.
The second incident occurred yesterday just before 4pm. A 66-year-old man near Marton rolled his quad bike, suffering neck and chest injuries.
He is currently in Whanganui Hospital in a serious condition.
Last year New Zealand hit a record high with 14 quad bike deaths. More recently, a man from Eketahuna died in October after coming off his quad bike.
The same day, another man in his late 60s living near Nelson, also died after coming off his quad bike.
A study published in the Australian and New Zealand Journal of Public Health earlier this year, canvassed quad bike deaths between 2007 and 2012.
There were 101 quad-fatalities, with 69 in Australia and 32 in New Zealand.
On average, five Kiwis die every year as a result of quad bike accidents on farms, and a further 850 are injured.
The study found both countries had several contributing factors in common including that most fatalities involved males, a large majority occurred on farms, more than half were work-related and approximately one third involved head injuries, with helmets rarely worn.