Idarubicin (IDA) is an antineoplasic drug commonly used to treat hematologic diseases. Because of its relative lipophilic properties, this anthracycline is also used in transarterial chemoembolization (TACE) as part of hepatocellular carcinoma (HCC) treatment. But TACE requires injected volume to be reduced to restrict systemic diffusion and side effects. The aim of this study was to determine the stability of a highly concentrated aqueous solution of IDA, stored in polypropylene syringes between 2 °C and 8 °C. Analyses were performed with an HPLC system combined with UV detector and mass spectrometer. Forced degradation was used to investigate potential degradation products. This study demonstrated 7 days of stability after storage in previously mentioned conditions. This conservation is long enough to anticipate drug preparation and facilitates pharmacy organization.