Objective: The aim of this study was to evaluate whether the bonding properties of the adhesive luting agents have an effect on the retention of titanium copings on questionable preparations with different convergence angles (10˚,14˚) and different occluso-gingival height (3mm,5mm) or not. Material and methods: A total of thirty freshly sound extracted human mandibular second molars molars were equally divided into three equal groups according to the preparation convergence angle and height. Group (I): 10˚, 5 mm height. Group (II): 10 ˚, 3 mm height. Group (III): 14˚, 5 mm height. . Each group was subdivided into two equal subgroups of 5 samples each according to the type of adhesive system. Subgroup (A) Total etch adhesive resin cement (Rely X ARC). Subgroup (B) Self adhesive resin cement (Rely X unicem). The Samples were prepared in a standardized manner using an engineering lathe machine with triangular carbide cutting tool according to the tested groups the occlusogingival height was reduced into two occlusogingival heights 3mm and 5mm and the degree of convergence angle was prepared by two different degrees 10˚ and 14˚.A total of thirty titanium copings were fabricated using CAD/CAM manufacturing techniques (scanning, computer-aided design, computer aided manufacturing ). Following manufacturer's recommendations for each cement, two adhesive luting systems were evaluated: total etch adhesive resin cement (Rely X ARC), and self adhesive resin cement (Rely X Unicem). The later cement did not require any special treatment of dentin, whereas the former (Rely X ARC) specimens, a dentin bonding agent (Adper Single Bond 2) was applied and etchant (Scotchbond Etchant). A 3 kg load was used to apply a standardized static pressure for 5 minutes over each cemented coping using a custom made cementing device. The copings of all test groups were dislodged along the long axis of the tooth with a universal testing machine at room temperature with a crosshead speed of 0.5mm/min until failure. The force at dislodgement per mm2 (Mpa) was determined by applying tensile force for each coping, and the force in Newton (N) required to remove the copings was recorded and data were recorded using computer software. Results: According to the effect of abutment height, it was found that the retentive force mean value of 5mm height recorded higher mean value than 3mm height. significantly (ًp<0.05). Regardless to convergence angle or adhesive system. According to the effect of preparation convergence angle, it was found that convergence angle 10˚ recorded higher mean value than taper 14˚ non-significantly (ًp>0.05). Regardless to the height or the adhesive system. According to the effect of adhesive system , it was found that total etch recorded higher mean value than self adhesive cement significantly (ًp<0.05). Regardless to height or convergence angle.Conclusion: The height of the preparation plays an important role in the retention of the titanium copings, while the degree of convergence angle between 10˚-14˚ has no considerable effect on the retention of full coverage titanium crowns when cemented with adhesive systems. Total etch adhesive resin system provided better adhesive properties than self adhesive system.