Radioembolization of tumors after selective catheterization has been proven to be an effective therapy in nuclear medicine. The goal of the study was to evaluate the ¹⁸⁸Re labeling and in vitro and in vivo stability of several representative non-degradable polymeric microspheres and biodegradable particles. The biodistribution after i.v. injection in Wistar rats revealed excellent in vivo stability with low uptake in the non-target tissues over 48h for some polymeric particles and especially for biodegradable human serum albumin microspheres.