A Brazilian federal judge has ordered President Jair Bolsonaro to comply with local rules to wear a face mask whenever he is outdoors in the capital of Brasilia.
During recent weekends, a sometimes unmasked Bolsonaro has joined throngs of people protesting against Brazil's Congress and Supreme Court.
He has often visited bakeries and outdoor food stalls, drawing crowds around him.
Judge Renato Coelho Borelli said in his ruling that Bolsonaro "has exposed other people to the contagion of a disease that has caused national commotion".
Brazil's federal district requires people to wear face masks in public to help control the spread of the coronavirus.
Failure to comply carries a possible daily fine of $US390 ($A561).
Bolsonaro often does wear a mask at public events, unlike some other heads of state in the Americas including US President Donald Trump, Mexico's Andres Manuel Lopez Obrador and Argentina's Alberto Fernandez.