Three buses believed to be carrying expelled American diplomats have departed from the US Embassy in Moscow.
Before the morning departure, journalists outside the embassy compound saw people leaving the residences, placing luggage on lorries.
Russia last week ordered 60 American diplomats to leave the country by today in retaliation for the United States expelling the same number of Russians.
The moves were part of a deepening dispute over the nerve-agent poisoning in Salisbury of Russian former double-agent Sergei Skripal and his daughter Yulia.
The UK alleges Russian involvement, which Moscow vehemently denies.
More than 150 diplomats have been expelled by Britain and its allies, and Russia has ordered reciprocal moves.