The influence of a fiber post‐restored abutment tooth on the load capability of a three‐unit zirconia framework cantilever fixed dental prosthesis (cFDP) was evaluated after simulated clinical function. Human lower sound premolars (n = 64) were distributed, in equal numbers, to four experimental groups: two vital abutment teeth (group I; control); mesial abutment tooth post‐restored (group II); distal abutment tooth post‐restored (group III); and mesial and distal abutment teeth post‐restored (group IV). All specimens received an adhesively luted three‐unit cFDP of veneered zirconia. Simulated clinical function was performed by two subsequent sequences of thermal‐cycling (2 × 3,000 cycles) and mechanical loading (1.2 × 106 load cycles from 0 to 50 N) (TCML). Four specimens failed during TCML (one in each of groups I and IV and two in group II). The maximum load capability ranged from 365 to 538 N and was not significantly different between groups. Specimens with post‐restored abutments failed mainly because of abutment tooth fracture of the distal abutment. The presence or position of post‐restored abutment teeth has no significant impact on load capability of all‐ceramic three‐unit cFDPs. The risk of tooth fracture of the distal abutment teeth of a cFDP was significantly increased when one abutment tooth, irrespective of its position, was post‐and‐core restored.