Pepsin is a proteolytic enzyme that is commonly used in the food industry. Pepsin can be extracted from the stomach of tuna fish. Tilapia has a high protein content. Thus, it can be used as an alternative for surimi paste raw materials. This study aimed to determine the concentration of pepsin enzyme from tuna stomachs that could improve the quality of red tilapia surimi paste. The concentrations of pepsin added to surimi were 0%, 2.5%, 5.0% and 7.5% (v/w). The effect of adding pepsin was examined by salt soluble protein, pH, chemical and physical characteristics, whiteness degree, and the sensory acceptances of the generated tilapia surimi. The results showed that the addition of pepsin to surimi paste significantly increased the strength of surimi gel, folding test, and salt-soluble protein. Surimi with the addition of 2.5% pepsin showed the most acceptable results compared to 0% pepsin with 77.99% moisture content, 14.88% protein content, pH 7.01, salt-soluble protein 0.833 mg/mL, gel strength 2,030.04 g/cm2, whiteness 88.3%. The sensory test of tilapia surimi with the addition of 2.5% pepsin revealed the appearance value of 7.80, the folding test of 5.57, and the bite test of 6.4.