Nanotechnology as a new field of science is broadly exploited in a plethora of commercial uses. Biocompatible nanomaterials are also attractive for medical applications. However, an exact processes related with their biodistribution within the body needs to be examined. This study deals with future perspectives for biodegradable nanoparticle on the example of fluorescent ZnO NPs (zinc oxide nanoparticles), doped with europium (Eu) ions. The aim of the study was to evaluate distribution processes of biodegradable ZnO:Eu NPs within the living organism. ZnO:Eu NPs were administered intra-gastric (IG) (10 mg/ml, 0.3 ml/mouse) to adult Balb-c mice (n=35) and following 3h, 24h, 7d, 14d and 1m mice were sacrificed and internal organs were collected, as was described before . For determination the excretion patterns of these nanostructure, ZnO NPs were orally administered to mice (n=24) with further measurement of zinc content in the feces of tested animals. All procedures were conducted according to local and EU regulations and approved by the LEC 44/2012. No pathological/behavioral changes were observed in mice. Biodegradable ZnO:Eu NPs revealed ability to overcome majority of physiological barriers in the organism, which renders them invaluable tool for biomedical applications. After 3h the presence of fluorescent NPs was already observed in key tissues and the peak of NPs distribution was observed at 24 h after IG in majority of tissues, including brain. Moreover, obtained results revealed fast and efficient clearance of ZnO NPs from the living organism, even following multiple administration of nanostructures (up to 4d after IG).