Last week, the Internal Affairs Minister Penisimani Fifita referred to the survey conducted by the Ma'a Fafine mo e Famili organisation at the launch of a 16-day anti-domestic violence campaign.
The project co-ordinator for the organisation, Gabriella 'Ilolahia, said the study, which was released in 2012, had been criticised by members of the public for exposing a shameful aspect of Tonga's culture.
But she said it showed that violence did exist in Tonga and could no longer be ignored.
"They're surprised to hear that we can talk about the violence now.
"When we started work, my mother started this work, it was almost taboo to talk about it.
"Some people still don't believe, I think they're the perpetrators, they're the ones living in denial, they're the ones who are saying that 'it doesn't exist, why we are broadcasting all of this? Why should the world know that this has happened?'"
Gabriella 'Ilolahia said reporting domestic violence and prosecuting offenders was crucial to stemming the number of cases.