Superparamagnetic iron oxide nanoparticles (SPION) have attracted a lot of interest due to their widespread biomedical and diagnostic applications. Coating the SPIONs with various surface layers can provide an interface between the core and the surrounding environment. The aim of this study was to examine the in vivo behaviour of dextran-coated iron oxide nanoparticles (D-IONPs) in aqueous suspensions. The SPIONs stabilized with dextran (D-IONPs) were synthesized in aqueous solutions by co-precipitation method. The average grain size deduced from transmission electron microscopy is 7.5 nm. The hematological parameters registered for the rats exposed to D-IONPs at 1 ml/kg have had values approximately equal to those examined for the control specimen. The architecture of liver and kidneys was not affected after one day of intraperitoneal injection of D-IONPs compared to the reference group. After 21 and 28 days respectively from the administration of the D-IONPs solution, the liver and kidneys from the injected rats showed a normal aspect without abnormalities compared to the rats uninjected. Our findings suggest that the administration of 1 ml/kg D-IONPs did not cause any toxicological effect since the parameters of renal and liver function were in the normal range as reported to the control group.