The inaugural Marlborough wine competition has attracted more than 424 entries.
Director Belinda Jackson says they include 140 sauvignon blanc wines and 76 pinot noir wines.
She says one aim of the competition is to demonstrate to global wine markets, that Marlborough is made up of a number of sub regions which produce different styles of wine.
Ms Jackson says following each day's judging, which begins on 1 September, the public will be invited to taste the wines, in exchange for a donation towards Marlborough Riding for the Disabled.