Background: Composite resin consists of matrix resin, coupling agents, filler, and other supportive materials. Filler is inorganic material, non-biodegradable, non-renewable, non-recyclable that contained in composite resin. Natural fiber can be used as substitute for inorganic filler, such as sisal fiber (Agave sisalana). Purpose: This study aimed to determine the difference of tensile strength between nanosisal 60% filler and nanofiller composite resin. Methods: Sisal fiber converted into nano-sized sisal, labeled as nanosisal. Nanosisal mixed with Bis-GMA, UDMA, TEGDMA, Champhorquinone (Sigma Aldrich). We used nanofiller composite resin (Z350 XT 3M ESPE) as control and 10 samples that were divided into 2 groups. Nanosisal composite resin 60% filler labeled as group A, nanofiller composite resin labeled as group B. Extracted premolar teeth were prepared to class V (G. V. Black classifications) then filled using those two materials, each material for 5 teeth. The samples were tested for tensile strength using a Universal Testing Machine (UTM). Data was analyzed by Independent Sample T-Test. Results: The mean of tensile strength of nanosisal 60% filler composite resin was 4.39 MPa, and nanofiller composite resin was 1.23 MPa. There was a significant difference in data analysis (p = 0.004; p < 0.05). Conclusion: The result showed that nanosisal 60% filler composite resin has higher tensile strength rather than nanofiller composite resin. Nanosisal 60% filler composite resin could be bonded to tooth structure using total etch adhesive material.