Rosara Joseph (Christchurch) won her fourth elite women's title in 1hr 42min 45sec from Karen Hanlen (Whakatane) in 1hr 44min 26sec and Katherine O'Neill (Rotorua) in 1hr 49min 55sec.
Carl Jones (Rotorua) won his first men's elite in 1hr 51min 4sec from Dirk Peters (Rotorua) in 1hr 53min 7sec and Mike Northcott (Tokoroa) in 1hr 53min 21sec.
Anton Cooper (North Canterbury) won his first under-19 title in 1hr 25min 21sec.
Joseph (29), who finished ninth at Beijing, has dominated women's cross-country in New Zealand since 2005 and will be at the London Olympics.
She has spent the past four years working on her PhD at Oxford University and only recently settled back in Christchurch.
She overcame technical problems in the mud in the Bethunes Gully forest during the second of the four laps.
"I had mechanical problems and the wheel wouldn't turn over properly," Joseph said.
"It gave me a scare."
Hanlen (30), a physiotherapist, is a first-year mountain biker.
But she comes into the sport with a lot of experience in endurance sport.
She won the Kepler Challenge in 2003.
"I was better in the mud than Rosara and was able to run up the steep hills,"she said.
"But she is more skilled."
It was a temporary hiccup for Joseph, who took control after the pair passed the halfway point together.
She was 1min 11sec in front after three laps and won the race by 1min 41sec.
In the men's race, Jones and Peters took off like frightened rabbits at the start and left defending champion Mike Northcott struggling after a lap.
After a lap Jones led Peters by 6sec and Northcott was 37sec back.
After another lap Jones had increased his lead to 17sec over Peters and Northcott was 1min 16sec back and out of the race.
Peters caught Jones on the third of the five laps and they were together with two laps left.
Jones moved into a 44sec lead on the penultimate lap and had a margin of 2min 3sec at the finish.
Jones (22) has an ambition of getting to the London Olympics.
"I am fitter and faster than I have ever been before and I really wanted that elite title," he said.
Cooper (16) has set his sights on the 2016 Olympics in Rio de Janeiro.
The Christchurch Boys High School pupil won the under-19 title by 5min 4sec.
He raced on his training bike because his racing bike was locked in a Christchurch bike shop when the earthquake struck.
Mary Gray (Dunedin), an Otago Girls' High School pupil, won her first New Zealand title in the women's under-19 grade in 1hr 26min 24sec.
Other champions from Otago were: Laura Bridger (Dunedin), women's under-17 (1hr 7min); Kate Fluker (Queenstown), senior women (1hr 28min 9sec).
