Labour Party MP Clare Curran has been asked to leave the debating chamber on Tuesday for wearing a Highlanders rugby jersey in the House.
Parliament's rules dictate that male MPs must wear a jacket and tie and female MPs normal business attire.
Speaker Lockwood Smith told Ms Curran that she was not wearing appropriate business attire and ordered her to leave the House during Question Time.
"This House does have certain dress standards and it would not be acceptable for a male member to be dressed that way and it is totally unreasonable, therefore, to discriminate."
The MP for Dunedin South says is proud to wear the traditional blue, gold and maroon jersey, which has recently been replaced by a bright green one.
However, Dr Smith told Ms Curran it was not appropriate and she had to leave the debating chamber, but could return if she got changed.
Ms Curran says she wore the Highlanders jersey in a show of support for the people of Otago and Southland who she says don't like the new green strip.
She says expected she would get a reprimand, but being sent out of the debating chamber seemed disproportionate.
Green Party co-leader Metiria Turei left with Ms Curran, later tweeting that it was not a stunt and sexism in the House was continuing.