About a dozen anti-Trans Pacific Partnership protesters took to a roundabout at the southern entrance to Wanganui this morning.
The protest was to coincide with the arrival of deputy prime minister Bill English to the city.
The peaceful protesters rode bicycles around the roundabout on the intersection of Wikitoria Rd and the Cobham Bridge and waved placards at passing traffic.
Organiser Chris Cresswell said the groups had wanted to catch Mr English on his way through.
"It's (TPP) going to be extremely harmful to the country," he said. "It's opposed by multiple medical bodies and legal bodies."
An emergency physician at Whanganui Hospital, Dr Cresswell said one concern was that the agreement would undermine Pharmac and increase the cost of pharmaceutical drugs for New Zealanders.
"Drug companies would be able to challenge every decision made by Pharmac," he said.
He said Australia had faced a $50million legal challenge when it tried to introduce plain packaging on cigarettes.
"I think people are starting to wake up to the implications of this and seeing it's not just a radical element opposed to this. It's sensible people."
Dr Cresswell said more protests were planned throughout the day.
Mr English is due to speak at a Chamber of Commerce lunch in Wanganui this afternoon.
About six police officers were present at this morning's protest. "Everyone had the right to protest as long as they are doing it in a safe manner that's not disrupting the public,' sergeant Andy Reid said.
"As long as they're not breaking any rules and causing a problem, police will be leaving them alone."