Rosmarinic acid (RA) is a strong antioxidant compound that is present in many natural plant extracts. Despite its strong antioxidant activity, it had a limited use because of the low water solubility and chemical instability. Encapsulation technologies have been used for improving the solubility and long-term stability of bioactive molecules. Liposomes (LPs) and nanospheres (NSs) can encapsulate many types of molecules and can provide high bioavailability and are able to assure a sustained release for a long time. In this study, RA-loaded LPs and NSs were developed and characterized in vitro. Encapsulation efficiencies (EE) % of formulations were found 55.6% and 43.4% respectively. Release studies of RA, performed using pH 7.4 phosphate buffer for 24 hours through dialyse membrane were investigated and 74.2 +/- 2.11% and 83.2 +/- 1.91% drug release rates were obtained respectively. The stability studies were performed when the formulations were stored at three different temperatures for 3 months. The significant particle size increase and the zeta potential decrease were not observed in LPs and NSs after 3 months when stored at 4 degrees C (p > 0.05). Antioxidant activities were measured using DPPH center dot and ABTS(center dot)* radical scavenging effect and ascorbate-iron(III)-catalysed phospholipid peroxidation and the results were found to be favourable. Generally, RA could load the drug carrier systems successfully and it was concluded that the prolonged antioxidant activity could be sustained for 24 hours.