Objectives: this study evaluated the effect of dentin surface finish& thermocycling on the shear bond strength of two adhesive systems. a-Total-etching adhesive cement b-Self adhesive cement. Materials and Methods: Sixty sound freshly extracted molar teeth were collected and stored in saline until use.For the assessment of shear bond strength, the dentin samples were prepared by flattening tooth surface, till dentin surface was exposedFor shear bond strength testing (sixty discs samples) were divided into three groupsGroup (1): 20 teeth without any surface finish Group (2): 20 teeth with mechanical dentin surface finish using stone. Group (3): 20 teeth with chemical dentine surface finish using EDTA. Each group was further subdivided into two subgroup according to the type of cement which used for bonding, whether total etch or self adhesive.Subgroup (A): include 10 discs with total etch resin cement. Subgroup (B): include 10 discs with self adhesive cement Each subgroup was further divided into two halves, the first subjected to. thermocycling and the second not subjected to thermocycling.Cement the discs on prepared molars using adhesives. The cemented disc samples were then transferred to Lloyed universal testing machine for shear bond strength determination. Results were collected and tabulated and then statisticallyanalyzed to compare different groups. And then has been chosen the representative of each group to be photographed under scanning electron microscope to determine the origin and method of fracture in the samples. Results: 1-All groups with the (Total Etch) adhesiveshowedhigher shear bond strength than used the (Self Adhesive) adhesive.2- Dentin surface finish showed effect on the shear bond strength. 3-Exposure to thermal cycles weaker Shear bond strength. Conclutions: 1. Dentin surface finish was highly affected the shear bond strength, as shear bond strength among mechanical group was higher than EDTA followed by control group.2. Thermocycling (1500 cycles) influenced negatively the shear bond strength.3. Total-Etch Adhesive system is a better choice than Self adhesive system in achieving bonding to tooth structure.