Background and Objectives: Groundwater sources, as strategic sources of water supply, are of particular importance for human beings. Arsenic is a toxic and carcinogenic contaminant that has been reported to be widely found in groundwater sources. In recent years, adsorption property of nanoparticles has been used to remove arsenic. The present study was performed with the aim of assessing the arsenic reduction process in the aqueous environment under groundwater-like conditions using titanium dioxide (TiO2) nanoparticles (ANATASE). Methods: In this experimental study, using batch experiments, the effect of changes of time, nanoparticles concentration, and pH factors, were investigated on the changes in arsenic concentration in aqueous solution. The specific surface area of the adsorbent was 200-240m2/g. Data were statistically analyzed by measures of central tendency. Results: In this study, more than 90% of arsenic concentration in the solution, was absorbed after about 30 minutes of exposure to ANATASE nanoparticles, however, it took 60 minutes to reach drinking water standard level of arsenic (10μ g/L). Increasing adsorbent concentration caused an increase in arsenic adsorption. In natural pH range of groundwater, TiO2 nanoparticle can absorb near 100% of arsenic (200μ g/l), but, increase in pH increased this ability. Also, adsorption of arsenic by ANATASE nanoparticles was more consistent with the Freundlich isotherm. Conclusion: The results of the current study showed that TiO2 nanoparticles are efficient adsorbents for removal of arsenic from aqueous solutions under natural groundwater conditions.