Objects: The aim of this study was carried out to investigate the effect of different surface treatment protocols on bond strength of nano-composite as a repair material to two types of resin composite either nano-composite or hybrid resin composite at different aging periods. Materials & Methods: Total of 160 composite discs were prepared, the prepared discs were divided into two main groups (80 each) according to the type of composite used (C), nano composite (C1) and hybrid resin composite (C2). Each group was sub-divided into four subgroups (20 each) according to the surface treatment protocol (S) that was done on the discs, either no treatment (S1) (control), application of adhesive system (S2), application of 37% ortho phosphoric acid (S3) and diamond bur surface roughening (S4). Each sub group was subdivided into two classes (10 each) according to the time elapsed after repair (T), either immediate repair (T1) or three months after repair (T2). A polyethylene tube of 3 mm length and 1 mm internal diameter was used to act as mold for repair composite. Three cut micro tubes were placed apart on the surface of each treated substrate disc. Each tube was held in place with a tweezer during the packing of the composite using endodontic plugger. The packed resin composite in the cylinders was cured for 40sec. Using a sharp scalpel the polyethylene tubes were cut and removed away leaving composite cylinders of 1 mm diameter and 3 mm length bonded to the treated disc. Shear bond strength was testing. The resin-resin interface analysis was done using stereomicroscope. Data were collected, tabulat and statistically analyzed P≤0.05. Results: The diamond roughening with hybrid resin composite after 24 hours showed the highest μ-Shear bond strength mean value (36.07 ± 2.686) while the hybrid resin composite with no surfacetreatment (control) after 3 months showed the lowest μ-Shear bond strengthmean value (10.85 ± 0.9528). Regarding the composite type, the hybrid resincomposite recorded higher μ-shear bond strength mean value (17.14 ±1.263MPa) than nano-filled composite (14.16 ± 1.032 MPa). Regarding thesurface treatment, the diamond roughening group recorded the highest meanvalue (21.9±1.45 MPa) followed by bond application group (15.63±0.85MPa) then acid etch treated group (12.56±1 MPa) while control (nontreated)group recorded the lowest mean value (12.005±1.1MPa). Regardingthe storage time, the 24h aging time recorded higher μ-shear bond strengthmean value (18.1 ± 2.4 MPa) than 3months (12.95± 0.75MPa).Conclusion: The diamond roughening of the resin composite improved thebond strength of different types of resin composite to it with bond stabilityeven after aging for three months.The type of resin composite used for repairinfluences the bond strength to the repaired resin composite eitherimmediately or after aging. Lack of surface treatment of the resin compositebefore repair adversely affects the bond strength to the repaired resincomposite. Aging of the repaired resin composite affects the bond strengthto it with different treatment protocols.