The Dunedin event was one of 15 nationwide events to protest the TPPA, which is being negotiated behind closed doors between 12 countries, including New Zealand.
About 150 people - some holding holding placards or waving political party banners - gathered at the Octagon under the statue of Robbie Burns, on Saturday, to listen to speakers.
The biggest cheer was reserved for Dunedin City councillor and Green Party representative Aaron Hawkins, who called on the Government to release information about the TPPA.
''If the Government has nothing to hide, it shouldn't have anything to fear.''
Leaked documents from the negotiations raised concerns of the power foreign firms could wield in New Zealand, with the bulk-purchasing power of Pharmac just one example under threat, he said.
''This rally, and the movement around it, is not anti-trade, it is pro-democracy, it is gathering momentum, and the TPPA champions are scared,'' he said.
Mr Hawkins said lead negotiator David Walker would be visiting Dunedin in the coming weeks to talk to local business leaders as part of a ''charm offensive national tour''.
