In the medical field and especially for cancer treatment, intensive researches are performed to deliver the drug at the right position allowing reducing dose and side effects. The poor solubility in biological fluids of drugs obliges to encapsulate them into carriers showing an amphiphilic behavior. We work here with Pluronics that form micelles above the CMT and Hyaluronan(HA), a linear semirigid polyelectrolyte, widely found in the human body. It is currently investigated as a target-specific material because many malignant cancer cells over express HA receptors. DLS measurements have been performed as a preliminary structural characterization. A systematic increase of the hydrodynamic radius with the amount of HA from 120 Å for the pure P123 micelles to 180 Å with 1% of HA is observed. Only SANS and contrast variation will give a detailed characterization of the mixed HA /Pluronic aggregates and the effect of model drug molecules. In a fundamental point of view, such system can help to understand the forces governing the formation of complexes between polyelectrolyte and nonionic micelles.