Aerzen is a municipality in the Hamelin-Pyrmont district, in Lower Saxony, Germany. It is situated 10 kilometres (6 mi) southwest of Hamelin, and 7 kilometres (4 mi) north of Bad Pyrmont.
One of the biggest employers in the region is Aerzener Maschinenfabrik GmbH, a manufacturer of blowers and compressors. As of April 2008, they had an estimated 1000 employees.
- Börries von Münchhausen (civil servant) (1587-1646), secret Kammerrat, mortgage holder of the Office Aerzen
- Gustav Karl Wilhelm Siemens (1806-1874), member of the National Assembly in Frankfurt
- August Heissmeyer (1897-1979), Obergruppenführer and General of the Waffen SS