In this study the effects of Fe2O3 and Fe3O4 magnetic nanoparticles and EDTA on urease activity was investigated. The effect of nano-Fe2O3 and nano-Fe3O4 on urease activity were investigated. Urease activity was studies by UV-Vis spectrophotometry at 40 °C at pH = 7.2 using sodium phosphate as buffer. Measurements were carried out using 0.075 mg/ml of urease and a range of nano-Fe2O3 and nano-Fe3O4 concentrations between 0.002-0.006 mg/ml. It was found that by increasing the concentration of nano-Fe2O3 and nano-Fe3O4, urease activity will be decreased. On the other hand, nano-Fe2O3 and nano-Fe3O4 act as non competitive inhibitor for urease. Urease protection studies were corried out by using different concentration of EDTA (0.004-0.008 mg/ml). It was shown by increasing the concentration of EDTA, the activity of enzyme increased.