An appeals court has ruled that the world's largest retailer must face a class action lawsuit, with discrimination claims from up to 1.5 million existing and former staff.
If Wal-Mart loses, it will have to pay damages worth billions of dollars.
Judge Martin Jenkins said sufficient evidence existed of discriminatory practices dating back to 1998 to support the case going to trial.
He said: 'Factual evidence, statistical evidence and anecdotal evidence present significant proof of a corporate policy of discrimination and support plaintiff's contention that female employees nationwide were subjected to a common pattern and practice of discrimination.'
The retail giant said it did not have a policy discriminating against women and it would appeal against the verdict.
Last year, the retailer had to pay about US$78 million (£39.6 million) to workers after a court found it guilty of failing to pay staff for working during breaks.