In a study, researchers say almost 1,000 men across europe had no transmission of the infection when their partner was treated to suppress the virus.
The study was conducted on 75 clinical sites in 14 European countries between September 2010 and July 2017. The couples had sex without condoms or other forms of protection.
An effective antiretroviral treatment has proven to prevent the transmission of the aids virus in all-male couples - where one partner is HIV positive - who have unprotected sex, a study published on Thursday shows. The management of HIV/AIDS typically includes the use of multiple antiretroviral drugs in an attempt to control HIV infection.
An earlier study proved the same thing among heterosexual couples. And before that, a pivotal study in 2015, this one focused primarily on heterosexual couples, found only four transmissions of HIV between an infected person and his or her partner.
The findings support the global U=U (undetectable equals untransmittable) campaign, which has argued that effective ART means people with the virus can have sex without the fear of transmitting it to partners.
The study is the latest scientific inquiry assessing HIV risks between gay partners - where one tested HIV-positive and the other negative.
While 15 men among the 972 gay couples tested HIV-positive throughout the study, genetic testing showed the virus had been transmitted sexually from an outside partner not involved in the treatment.
He said the research drives home an important message: "ART leads to good health".
"Our findings provide conclusive evidence for gay men that the risk of HIV transmission with suppressive ART is zero", said Alison Rodger, a professor at University College London who co-led the research.
HIV-suppressing medication could stop sexual transmission of the AIDS virus among gay couples - even if they had sex without condoms.
AIDS has killed 35 million people since it emerged in the 1980s and 78 million people have been infected with HIV.
She said this "powerful message" could help end the HIV pandemic by preventing the virus' transmission in high-risk populations. "We think this is vital to addressing stigma". However, the number of new infections stubbornly remains at around 1.8 million cases worldwide per year.
"It is impossible to overstate the importance of the findings about this crucial treatment", explained Dr Michael Brady, Medical Director at Terrence Higgins Trust, in a statement provided to RightsInfo. "We need to have universal access".