In recent years, there has been increasing concern about the usage of a broad range of organic substances, heavy metals and aromatic compounds in the aquatic environment due to their wide distribution and potential adverse health effects. The presence of toxic contaminants in water effluent, even at very low concentrations, is extremely harmful and undesirable. Various treatment processes have been investigated to reduce these toxic pollutants from wastewater. Because of the chemical stability of the contaminants, these technologies have proved to be ineffective for handling waste effluents. Nanotechnology offers the possibility of efficient removal of pollutants as nanoparticles have a smaller size and higher adsorptive surface area. From the past few years, nanoscale iron oxides such as magnetite, maghemite, and hematite have been used for the separation and removal of organic and inorganic contaminants. In this review we summarize the use of iron oxide nanomaterials performed over the last few years for the removal of dyes, heavy metals and aromatic compounds.