Officials said the men were scheduled to meet on Monday in Wana to discuss ongoing efforts to negotiate peace between Pakistani forces and the fighters.
The government is encouraging moderate tribal elders to broker a ceasefire in the region, but there has been little sign of success.
Gunmen killed three of the tribal leaders at a market in Wana, the region's main town, while the other five were shot to death in attacks at their homes in a town north of Wana, a security official said.
Security forces have fought intense battles with fighters in South Waziristan since Pakistan became a close ally of Washington in its war against terrorism following the September 11, 2001, attacks in the United States.
The government has accused Baitullah Mehsud, a South Waziristan-based tribal leader with links to al-Qaeda, of organising the December 27 assassination of Benazir Bhutto, a leading Pakistani politician supported by the United States.