Fans have spent 960 million reais (around $290 million) on 4.3 million tickets, Rio 2016 ticketing director Donovan Ferreti said on Saturday, Xinhua news agency reported.
Another 1.7 million tickets are still available.
The figure is still some way short of the mark set at the London 2012 Games, when 86 per cent of total tickets were sold.
“The ideal scenario would be to sell out all events but if we reach the level of London, we will be happy,” Ferreti said.
Ticket prices for the August 5-21 Games range from less than $20 for sailing, tennis and modern pentathlon to $1,400 for the best seats at the opening ceremony.