Background: Composite resin is a restoration material that is commonly used to replace the missing part of teeth because it has a high aesthetic value. Sisal is one of the natural fibers used as an organic filler material because it tends to be as a mechanical amplifier to the matrix. The disadvantages of inorganic fillers are such as the glass is non-degradable, non-renewable and non-recyclable, as well as the energy process is dependent on fossil fuels, has very high pollutant emulsions which harm the health and the environment. For this reason, this study aims to determine the effect of the amount of volume filler (wt%) 60%, 65%, 70% towards flexural strength of nanosisal composite resin. Methods: 20 samples were involved and divided into 4 groups. Group I was given composite resin nanofiller synthetic. Group 2,3,4 were given nanosisal composite resin with filler volume 60%, 65% and 70%. Flexural strength examination were performed in each group using Universal Testing Machine. Collected data was then analyzed using oneway ANOVA. Results: Data showed flexural in group I, 13,85 ± 10,68; Group II, 20.33 ± 11.75; Group III, 21.02 ± 5.89; Group IV, 14.64 ± 7.11. Data analysis using oneway ANOVA showed that there was no significant difference between the first group and the third group. Conclusion: There is no effect of volume amount of filler (wt%) 60%, 65%, 70% to nanosisal composite resin flexural strength.