The goal of the present research is to study the hemocompatibility of magnetic nanoparticles (MNPs) in model systems in vitro. Materials and methods. Magnetite nanoparticles and magnetite colloidal solutions were used in 0.9% NaCl in concentrations 0.2, 2.0 and 20.0 mg/ml. The study was performed with heparinized human whole blood, 1 ml of which was mixed with 1 of ml nanoparticles/physiological solution. Measurements were made directly after mixing, and then 1, 2.5 and 5 hours later. The amount of reactive oxygen species (ROS) was measured with luminol-dependent chemiluminiscence (CL). An erythrocyte aggregation index was calculated. For the assessment of hemolytic properties, a hemolysis coefficient was calculated based on optical density of the plasma. The nanoparticless surface protein layer investigation was performed with IR-Fourier spectroscopy. Results. Nanoparticles decline CL in time- and concentration-dependent manner. Erythrocyte aggregation stability grows, but concentration and/or application time increment leads to significant hemolysis. IR-Fourier spectroscopy data shows albumin as main component of protein crown, whose conformationc hanges in time. Given data proves safety of studied MNPs in relation to examined parameters in low (0.2 and 2.0 mg/ml) concentrations up to 2.5 hours interaction. This allows us to treat these MNPs as a promising agents for further use in medical practice after completing examinations related to other homeostasis indicators.