This study aims to synthesize Platinum nanoparticles (Pt NPs) using Olive leaves extract's environmentally friendly approach. UV-Visible spectroscopy has been used to follow the turning of Pt +4 ions to Pt0 NPs. X-ray diffraction (XRD) has been used to investigate the as-synthesized Pt NPs and its cubic face-centered structure crystallinity. The average size of nanoparticles was 9.2 nm, calculated by transmission electron microscopy (TEM). The activity of as-synthesized Pt NPs has been examined by inhibition of Serum Aspartate Aminotransferase (AST) level in patients with chronic liver disease and control group, The AST (mean= 12.8051.642) demonstrate a very significant rise (p < 0.01) in the results. In chronic liver patients with Pt NPs, serum AST activity was significantly lower (p < 0.01) than in patients without Pt NPs (mean=13.4582.360). The present study concluded that Platinum nanoparticles play a great role in inhibition of AST.