Cuba is pulling thousands of doctors out of Brazil, after what it called "contemptuous and threatening" remarks by president-elect Jair Bolsonaro.
The far-right leader, who takes office on 1 January, had questioned the doctors' qualifications.
He also accused Cuba's communist government of keeping 75% of their pay, and refusing to let their families join them.
The pull-out could disrupt healthcare for millions of Brazilians.
Why were so many Cuban doctors in Brazil?
Healthcare is Cuba's most lucrative export. The "More Doctors" aid programme operates in 67 countries, and makes the island $11bn a year.
Around 8,000 Cuban doctors have been working in Brazil's poorest and remotest areas under the scheme.
Cuba has said they will all be summoned home by the end of December. However, a Brazilian diplomatic source told AFP that 2,000 will likely stay put due to personal ties.
Brazilian mayors have warned that up to 30 million people are facing a care crisis - many in areas where local doctors refuse to go.
The first 196 doctors to leave have already been greeted in Havana by Cuba's deputy health minister.
Cuban news agency ACN said the medics were "happy to have fulfilled their mission," but "worried about what awaits the [Brazilian] people with the newly-elected president".
Brazil's health ministry said on Friday that it would start selecting local doctors to replace the departing Cubans later this month.