The advantages of bio-compatibility and hydrophilicity make hydrogels become biomaterials for many medical applications. UV polymerized PAA-Alg-Si (Polyacrylic-acid-Alginate-Silica) hydrogels have the potential to be used to repair the damaged articular cartilage due to the properties of low friction and high mechanical strength. The weight ratios of Silica in PAA-Alg-Si hydrogels have effects on the mechanical properties of PAA-Alg-Si hydrogels. In this study, the fracture resistances of UV polymerized PAA-Alg-Si hydrogels with different Silica weight ratios (0 %, 6% and 16%) were investigated by using single notched tensile tests. Hydrogels were considered as viscoelastic materials in this study. Fracture resistance is defined as the fracture work (N-mm) required to create one unit (mm2 ) of new fracture area during single notched tensile test. The fracture work was calculated by subtracting the estimated viscoelastic dissipation work from the total work between loading and unloading force-displacement curves of single notched tensile tests. The fracture resistance of the aforementioned hydrogels (Silica weight ratios 0 %, 6% and 16%) are 2.1E-05, 1.3E-05 and 1.7E-05 N-m/mm2 respectively.