.su was assigned as the country code top-level domain for the Soviet Union in 1990. It remains in use today, even though the Soviet Union itself no longer exists, and is administered by the Russian Institute for Development of Public Networks.

In 2001, the managers of the domain stated that they will commence accepting new .su registrations, but it is unclear whether this action is compatible with ICANN policies.

New .su registrations cost US$100.