The Guardian reported Friday the blogger in Lagoa da Prata in the state of Minas Gerais has published 300 names of supposed infidelity victims on the social networking Web site Orkut.
Not all of those named agree they were victimized by their lovers, the British newspaper said.
"My wife is a Catholic and a worker," an unnamed male victim said of his name's appearance on the blogger's list. "I have never had cause to doubt her."
One woman whose lover's name appeared on the list said the online posting nearly ended their relationship.
"They put his name and his nickname (on the list)," said the woman, who wished to remain anonymous. "We fought ... (and) we nearly separated."
Police in Lagoa da Prata are trying to identify the blogger, The Guardian said.