
It was billed as the "final battle" against government's plans to amend the Constitution.
Their protest march started at the PAD rally site at Makkhawan Bridge in the morning and ended at Democracy Monument, a few kilometres away.
Several thousand people were estimated to have taken part, and the number grew as the procession moved along.
Hundreds of police stood by along the route. Unlike previous marches, there was no attempted intervention by pro-government mobs.
Protecting the Constitution
Some passers-by and street vendors waved to the protesters.
Somsak Kosaisuk, a PAD leader, describes attempts to alter the Constitution "a coup without the use of military force". He says the group intends to protect the constitutional monarchy.
Somkiat Pongpaiboon, another PAD leader, says its "final battle" will begin as soon as the government submits a motion to Parliament for charter changes.
The gathering observed a minute of silence.
In a statement released yesterday, the PAD says the gathering at Democracy Monument is in honour of those who died protecting democracy and fighting dictatorship.
The procession later moved to Temple of the Emerald Buddha, where a brief religious ceremony was performed.
The PAD later returned to the bridge rally site.