These were for vacancies in the 6th Congress of the Philippines; the winners were to serve the rest of the term, which had ended on December 30, 1969.

These were the last special elections until the proclamation of martial law by president Ferdinand Marcos in 1972.

All seats in the House of Representatives were elected from single member districts, under the first-past-the-post voting system.

The congressman from the old Davao's at-large congressional district was free to choose which province he'd continue as an incumbent on.

[1] Duterte was then Secretary of General Services, had previously served as governor of Davao, and wanted to revive his political career, but was defeated by Loyola.