Objective: This study aimed to compare both microleakage and fracture strengths of polyetheret-herketone crowns manufactured via conventional composite layering and different computer-a-ided design and computer-aided manufacturing veneering techniques on polyetheretherketone cores. Materials and Methods: In total, 40 cores with 0.7-mm thickness were milled from polyethe-retherketone discs and separated into 4 groups: layering with composite resin, computer-aided design and computer-aided manufacturing-fabricated lithium disilicate veneer, computer-aided design and computer-aided manufacturing-fabricated hybrid ceramic veneer, and computer-a-ided design and computer-aided manufacturing-fabricated feldspathic veneer. Then, all cores were air abraded and an adhesive has applied to these surfaces. After the cores were connected to veneers, thermomechanical aging was applied in a chewing simulator. Evaluation of microlea-kage and fracture strength was performed via micro-computed tomography analysis and univer-sal test machine, respectively. One-way analysis of variance was used to detect any statistically significant differences between test groups. Also, failure modes and the correlation between mic-roleakage and fracture strength data were analyzed statistically. Results: Statistical analyses between the groups showed significant differences for both micro-leakage and fracture strength values. The lowest microleakage was in the computer-aided design and computer-aided manufacturing-fabricated hybrid ceramic veneer group (0.02 ± 0.01 mm3). The highest microleakage was in the layering with composite resin group (0.56 ± 0.21 mm3). The lowest fracture strength values were in the computer-aided design and computer-aided manuf acturing-fabricated feldspathic veneer group (620.58 ± 114.02 N). The highest fracture strength was in the computer-aided design and computer-aided manufacturing-fabricated lithium disili-cate veneer group (1245.82 ± 197.75 N). Also, there was no correlation between the microleakage and fracture strength groups. Conclusion: The use of computer-aided design and computer-aided manufacturing-fabricated lithium disilicate and hybrid ceramic veneers can be an alternative to layering when its other advantages are considered.