Australian-owned building supplies firm Bunnings has been accused of misleading New Zealand customers with its advertisements.
The Commerce Commission has filed 45 charges in the Auckland District Court.
The competition regulator alleged Bunnings advertised its products as the lowest priced on the market when that was not true.
It said its investigation looked into a range of advertising material, including television, radio and catalogues between July 2014 and February last year.
The case will be heard in court on 7 March.
The Commerce Commission was making no further comment.
Bunnings operates 46 stores around the country with about 3700 staff.
In a statement, the Australian parent company said it disagreed with the Commerce Commission's view of its lowest prices policy and would "defend our highly competitive price guarantee".