Bad Ems is a town in Rheinland Pfalz, Germany. It is the administrative seat of the Rhein-Lahn rural district and is well known as a spa on the river Lahn. Bad Ems is the seat of the Verbandsgemeinde Bad Ems-Nassau. The town has around 9,000 inhabitants.
In 2021, the town became part of the transnational UNESCO World Heritage Site under the name "Great Spa Towns of Europe", becacuse of its famous hot springs and 18-20th century architecture bearing testimony to the popularity of spa resorts in Europe during that time.