Mallard (29), the Otago captain, will guide the side from the front row against Canterbury in Temuka, and says it is a mark which has crept up quietly on her.
"It wasn't really something I was aiming for. I knew I was getting close and was on 40 something and I was surprised to have played so many," she said.
Her debut was against Southland in 1999, in Invercargill.
Coming off the bench in the second half is about all she can remember about the match, though Otago did win.
Mallard initially did not know if she would get 50 caps, after the disappointment of not making the Black Ferns this year to go to her second World Cup.
"I'm still enjoying it. I wasn't sure whether I would play again but I'm glad I did."
She missed out on the national side this year after a couple of front-rowers came out of retirement to get back into the black jersey.
"The selectors sort of decided that I didn't have the skill set they wanted. Mind you, they did all right without me. It was a bit sad watching them, thinking I could be there, but I was still proud of them all. They did a really good job."
Mallard, a tighthead prop, said there had been plenty of close-run things throughout her career with Otago.
She had been in a couple of NPC finals for Otago against Auckland when the side had just come up short.
"There was a final a few years ago when we were down by about five points and someone spilled the ball when going through a hole right near the end. I've never beaten Auckland and been on the wrong end of some hidings over the years."
Mallard, the daughter of Labour MP Trevor Mallard, said the loss of the NPC this year had been a real blow to the women's game, and if it does not come back, the chances of another New Zealand victory at the World Cup would decrease markedly.
"It is one of the main factors why we have done so well at the World Cup. The NPC is of a good standard. No other country has it and that is why we have done so well. We do not play many tests, so the NPC gives us that kind of experience."
Mallard, who started playing rugby at Wellington Girls' College, has finished her PhD and is now a teaching fellow in the physiology department at the University of Otago.
She will be looking to lead her side to a win tomorrow and get revenge after Canterbury won 20-15 in Temuka two weeks ago.
Otago was slow out of the blocks and needed to be awake straight from the kick-off against a Canterbury side bound to be full of emotion because of the earthquake, Mallard said.
OTAGO TEAM TO PLAY CANTERBURY
• Chloe Trubshoe, Natahlia Darling, Lucy Anderson, Rebecca Chittock, Nikita Fitzgerald, Victoria Nafatali, Zoey Berry, Georgie Gane, Maggie Crooks, Rachel Scott, Michaela Smith, Nicky Crawford, Beth Mallard (captain), Rachel Ovens, Nga Rapata.
• Reserves: Gemma Tuhega, Leyhana van Vugt, Sam Stewart, Angie Sisifa, Jo Amundsen, Charlotte Brock, Jaime Green.
