Propolis (bee glue) is a resinous hive product manufactured by bees from secondary plant metabolites. Modern science has discovered and confirmed numerous beneficial pharmacological properties of bee glue. In particular, propolis might be considered as an important source of natural bioactive compounds for cancer treatment, due to its potent apoptotic effect leading to death of cancer cells. However, the poor solubility of the active lipophilic secondary plant metabolites in aqueous/biological media seems to reduce their bioavailability, which is one of the main obstacles for application of propolis in cancer therapy. Block copolymer aggregates like micelles, vesicles, etc. have been intensively studied for development of chemotherapeutical formulations due to their ability to solubilize different anticancer compounds. Beside the huge number of copolymers, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymers are among the most attractive copolymers for preparation of drug and gene delivery systems. A novel micellar form of propolis based on a biocompatible PEO-b-PPO-b-PEO block copolymer (PEO26PPO40PEO26) was developed. Beneficially, all biologically active lipophilic constituents of propolis were solubilized with the aid of polymeric micelles in aqueous media. The micellar form of the propolis exhibits high in vitro cytotoxicity at relatively low concentrations.