The party was established on the eve of Christmas 1904 by the brothers Antun and Stjepan Radic under the name the Croatian People's Peasant Party.
A speech was delivered today by party leader Zlatko Tomcic.
In attendance were about 4,000 people, including political, public and religious figures. Tomcic gave a special welcome to incumbent President Stjepan Mesic, who is one of the 13 presidential candidates running in the January 2 elections.
Mladen Keser, another presidential candidate as well as an HSS member, was not given a special welcome.
The decision by President Mesic to posthumously decorate Vladko Macek, the second HSS leader, with the King Dmitar Zvonimir Order for his contribution to the creation of the Croatian state, was read at the event.