Judge Willem van der Merwe told a packed Johannesburg High Court in a verdict that was broadcast live on national television on Monday: “I find that consensual sex took place between the complainant and the accused.”
Zuma’s trial has fanned tensions in the ruling African National Congress (ANC) where he remains a popular figure and was until recently seen as the frontrunner to succeed Thabo Mbeki in 2009 as president.
More than 2,000 pro-Zuma supporters staged a noisy demonstration outside the court, the latest in a series of protests attesting to the grassroots popularity of a man many call “JZ”.
The 64-year-old anti-apartheid veteran had pleaded not guilty to raping his accuser at his Johannesburg home last November.
Supporters of Zuma demonstrate
But his lawyers said he did have consensual sex with the woman, a 31-year-old Aids activist.
Conviction for rape could have brought a jail term of up to 15 years.
Zuma was charged following a separate graft scandal last year which prompted Mbeki to sack him as the country’s second-highest official.
He is due to go on trial in July on the corruption charges, which he has denied and described as part of a shadowy political plot by his enemies in the ANC to end his presidential hopes.