In this work, a simple approach at oleuropein (OLE) extraction/concentration from olive leaves was proposed. OLE extraction yield was 5.4% w/w of dry leaves and a concentration of OLE of 20% w/w in the ethanol extract was obtained. Then, supercritical antisolvent extraction (SAE) was performed on the ethanol OLE solution, operating at different pressures between 100 and 200bar and temperatures between 35 and 60°C. SAE produced a powder rich in OLE up to 36% w/w at 35°C, 150bar. Precipitated powder showed different mean diameters dependent on SAE operating conditions: at 60°C, 130bar it consisted of micrometric and coalescing particles; at 35°C, 150bar it consisted of nanometric non coalescing particles. Therefore, OLE concentration was successful and its bioavailability should be improved by nanometric size of precipitates.