The laws criminalising sex between men had remained on the statute books despite the post-apartheid constitution of 1994, which made South Africa one of the first countries in the world to outlaw discrimination on the basis of sexual orientation.
The constitutional court's decision opens the way for gay men to seek compensation from the government if they faced charges during the period when the law and the constitution were at odds.
South African gay rights groups have welcomed the ruling.
The National Coalition for Gay and Lesbian Equality said it could open up adoption, marriage and other rights for homosexuals.
"The court has said that lesbians and gay men ... have a right to equality and dignity and privacy," said Zackie Achmat, the group's director.
The gay lobby is now supporting fledgling campaigns in other southern African countries like Zambia and Zimbabwe where homosexuality remains illegal and where senior politicians often verbally abuse gay campaigners.
Electric shock therapy
Under apartheid, sodomy could be punished with up to seven years in prison. Men were not even allowed to have casual contact at social gatherings that could be construed as homosexual behaviour.
The former South African military practised so-called "aversion therapy" on gay men, applying electric shocks to victims while they viewed images of naked men, a report on human rights abuses said last year.
Sex between women was never officially banned, but the court said it was symbolically stigmatised by the old laws.
Since apartheid ended, President Nelson Mandela's government has pushed to end all forms of discrimination.
The country's military protects the rights of gay and lesbian soldiers.
Earlier this year, the police were ordered to include a lesbian partner under a female officer's medical insurance.
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(09 Oct 98 | Europe)
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