Background: Composite resin is a restoration material consist of three major components such as matrix resin, coupling agents, and fillers. Inorganic fillers that commonly used have the disadvantages which are non-degradable, nonrenewable, and are highly dependent on fossil fuels. Natural fibers can be used as a substitute for fillers in composite resin. One that can be used is sisal fiber (Agave sisalana). Aims: This study aimed to determine the difference of attachment to email and dentin between nanosisal composite resin 60%, nanosisal composite resin 60% with coupling agent, and nanofiller composite resin. Method: This type of research is laboratory experimental and descriptive. Sisal fiber is converted into nano-sized sisal, labeled as nanosisal. Nanosisal mixed with Bis-GMA, UDMA, TEGDMA, Champhorquinone and Bisphenol A diglycidyl ether (DGEBA) as coupling agent. Nanofiller composite resin (Z350 XT 3M ESPE) as a control. The samples were divided into three groups and each group consist three samples. Nanosisal composite resin 60% as group A, nanosisal composite resin 60% with coupling agent as group B, and nanofiller composite resin as group C. Nine extracted premolar teeth were prepared for class V (G. V. Black classifications) and then filled with three ingredients, each material for three teeth. The samples were tested using a Scanning Electron Microscope (SEM). One Way Anova test were used for data analyzed. Result: Nanosisal composite resin 60% has an average attachment is 7.783μm, nanosisal composite resin 60% with coupling agents is 6.693μm, and nanofiller composite resin is 8.407μm. There were significant differences in data analysis (p = 0,027; p <0,05). Conclusion: The result showed that nanosisal composite resin 60% with coupling agent has greater attachment to email and dentin than nanosisal composite resin 60% and nanofiller composite resin.