As the optical properties of human whole blood are important parameters in knowing the optical response in the light-blood interaction, in this paper we have investigated the z-scan technique to determine the nonlinear refractive index (n₂) of blood smear with abnormal level of uric acid in-vitro. The measurements were fulfilled at 632.8nm using He-Ne CW laser with irradiation of 50mW. The results of nonlinear refractive index (n₂) are in order of 10(-9) cm²/W. Also we see that the obtained values of n₂ confirmed the previous studies using this technique.