Aim : To evaluate the effect of firing cycles on the shear bond strength and failure mode between veneering ceramic and zirconia core. Materials and method : Twenty-eight specimens of zirconia veneered with feldspathic ceramic were submitted to one (1-firing), two (2-firings), three (3-firings), or four (4-firings) firing cycles to sinter the porcelain. All the specimens were thermocycled for 300 cycles then collected, labeled and stored in distilled water for 48 hours before testing. Shearing test was done by compressive load applied at zirconia-veneer interface using a mono-bevelled chisel shaped metallic rod attached to the upper movable compartment of testing machine traveling at cross-head speed of 0.5 mm/min. Fractured specimens were ultrasonically cleaned, carefully checked under digital microscope (Dino-Lite, 241 Taiwan). All failures mode were analysed. Results: The highest mean value was observed in group A (6.69 MPa) and the lowest mean value was observed for group C (4.74 MPa). Statistical analysis revealed no significant difference between groups (P= 4.63). Statistical analysis among groups showed significant difference between groups A and B (P= 0.012), between groups A and C (P= 0.001), between groups B and C (P= 0.002), between groups B and D (P= 0.003). But no significant differences were found between groups A and D (P= 0.12) or between groups C and D (P= 1.4). Regarding mode of failure; 100% of the samples had cohesive failure in the veneering ceramic. Conclusions: Increase in firing cycles from 1 to 4 cycles had no effect on the SBS. There are no statistically significant differences in SBS between groups. In each group all of the failures (100%) were cohesive in the veneering ceramic, and the mode of failure did not tend to change as the number of firing cycles increased. KEY WORDS: Shear bond strength, Firing cycles, Zirconia, Veneer.