Considering extraction at industrial scale, conventional processes have some major drawbacks, such as insufficient recovery of extracts, extensive extraction duration, intensive heating and/or mixing, resulting in high energy consumption. Within this context, green technologies such as ultrasound are being increasingly investigated, aiming both at process intensification and meeting the goals of sustainable processes. The effectiveness of ultrasound has been demonstrated by a great number of authors. More specifically, ultrasound is used for natural product extraction (e.g. bioactive components such as essential oil, antioxidants, oil and dyes). Applied during extraction, ultrasound induce an increased extraction rate of monitored compounds compared to conventional extraction processes such as maceration. Reported mechanisms for this mass transfer enhancement are generally attributed to the effect of cavitation bubbles generated in the extraction media. Toma et al. demonstrated that power ultrasound (frequency comprised between 20 kHz and 1 MHz) specifically impacted cellular structures such as excretion hairs of pot marigold. Our study aims at a deeper understanding of ultrasound assisted extraction mechanisms. For this, we selected olive leaves as reference matrix. Effect of ultrasound has been assessed by submitting a single leaf maintained under an ultrasonic field (US probe, 20 kHz) at different treatment durations (5, 15, 30 and 60 min). Extraction was performed in an ethanol/water solvent (80/20, v/v), which is conventionally used to extract phenolic compounds. The media temperature was maintained at 25°C. After sonication, the solvent and extracted compounds was recovered to determine the polyphenol content and profile. Treated leaves were studied by histology and leaf surface observations. Preliminary observations tend to indicate strong histological differences according to ultrasound duration. Polyphenol release in the solvent also seems impacted by the ultrasound treatment, with a sharp total polyphenol increase of 0.001 mg EO/ml to 0.050 mg EO/ml (in equivalent oleuropein (EO)) for untreated leaves and US-treated leaves, respectively. In this study, the expected outcome is to link the structural differences observed on the treated leaves to the polyphenol extraction obtained.