Rally organiser Jen Olsen, speaking on the lawn in front of the Dunedin Railway Station, said ''it is not too late'' to stop the agreement becoming law.
''The TPP might be agreed on but it has not been signed.''
The agreement was as bad as opponents had feared, she said, especially as it potentially allowed corporations to sue the government if future law changes affected corporate profits.
Green Party leader Metiria Turei told the crowd all references to climate change had ''been obliterated'' from the agreement's latest form.
''There's still the opportunity for the Government to back away from this deal,'' she said.