Protease inhibitors play a vital role concerning proteases. Serine proteases are responsible for a variety of physiological processes and pathological conditions. Therefore, recently interest in protease inhibitors has increased, especially from natural sources such as plants. This study aimed at the identification of a potential candidate plant, the development of an assay procedure to detect the maximum serine protease inhibitory activity, and the characterization and partial purification of serine protease inhibitors from plant bark extracts.