Objectives: The study was performed to compare tensile bond strength obtained between composite and bone using a dentin bonding agent (Clearfil New Bond) after different pretreatments concerning surface roughening and etching times in vitro. Methods: Four mandibles of freshly sacrificed pigs were used to prepare twelve specimens each using trephane burs under constant water cooling. After preparation the surface was sanded. Fourty-eight bone specimens with a total thickness of 4.0 mm (± 0.5 mm) and a cortical layer of 1.5 mm (± 0.2 mm) were obtained under standardized conditions. Each twelve specimens were assigned to four experimental groups (Group A1: sandpaper 1000 (fine), etching 30 seconds; group A2: sandpaper 1000, etching 60 seconds; group B1: sandpaper 220 (rough) , etching 30 seconds, group B2: sandpaper 220, etching 60 seconds). Tensile bond strength of the dentin adhesive was measured 15 minutes after application and polymerization of the composite material (Clearfil Core) using an universal testing machine. Results: Following tensile bond strengths were evaluated (mean values and standard deviations, printed in MPa): Group A1: 4.54 (± 1.93); group A2: 4.25 (± 1.80); group B1: 2.34 (± 0.83); group B2: 0.67 (± 0.34). Statistical analysis showed a significant influence of the used pretreatment technique on tensile bond strength (p Schlagwörter: bond strength, dentin bonding agent, bone, pretreatment