Mondorf-les-Bains is a commune and town in south-eastern Luxembourg.

It is part of the canton of Remich. Mondorf-les-Bains is a spa town (hence its name), and has the only casino in Luxembourg.

As of 2005, the town of Mondorf-les-Bains, which lies in the south-east of the commune, has a population of 2,812. Other towns within the commune include Altwies and Ellange.

The spa welcomes thousands of visitors a year with its richly mineralized waters at 24°C (75°F). Set in a park of 36 ha (89 acres), its facilities are among the most modern in Europe. The waters are particularly suitable for the treatment of liver, gastric and respiratory ailments. In addition to a fully equipped fitness pavilion, there are also massage booths, saunas, indoor and outdoor swimming pools, solariums, Turkish baths and whirlpools. Treatments from algae wraps and lava-stone therapy to lymphatic drainage and ayurvedic rituals are said to be especially relaxing.