A rally opposing the proposed Trans-Pacific Partnership Agreement (TPPA) will start from the River Traders Market today.
Wanganui, one of 17 centres across New Zealand holding rallies, will hold a dance-march that will begin at the steel ball sculpture by the river at 10.45am.
Speakers will be Mairi Jay and Denise Lockett.
The TPPA is being negotiated by New Zealand and several other Pacific countries, including the United States, Japan and Australia.
Ms Lockett, who describes herself as a run-of-the-mill activist, said concern was growing worldwide over the TPPA, which she said was a corporate-driven pact.
Of the agreement's 29 chapters, only five dealt with trade, she said.
The others dealt with the "demands of the multinational corporations.
"Their demands require our government to deregulate in many areas to allow these corporations to operate in a manner which will be detrimental to the people, our environment and our health."
Ms Lockett said a particular concern was the threat to Pharmac and its ability to deliver affordable medicines.
"The huge pharmaceutical companies want to extend their patents and copyrights for a further 25 years, thereby preventing Pharmac from purchasing the cheaper generic versions. They also want seats on our Pharmac board."
In 2013, more than 100 doctors signed a letter to Prime Minister John Key, stating their unease in the matter. The Nurses Organisation also voiced concerns.