Background: The stratum corneum (SC) plays an important role in the skin barrier function. It acts as a protective barrier against water loss, eliminates foreign substances, micro-organisms and acts against harmful effects of UVR. Objectives: our aim was to study the impacts of UVA and UVB exposure in suberythemal doses on molecular structure, organization and barrier function of SC by following different Raman descriptors. Materials and methods: Twenty female volunteers aged from 20 to 30 years with healthy skin were enrolled for the study. 95 mJ/cm² UVA and 15 mJ/cm² UVB doses were applied on volunteers’ forearms. In vivo Raman measurements were performed at irradiated and control regions. Results: The impact of UVA and UVB irradiations were observed following several Raman descriptors, i.e. the ratio of vasymCH2/vsymCH2 (2885cm-1/ 2850 cm-1) for the organizational order of the lipid bilayer. Water content and mobility descriptors were obtained by calculating vOH/vCH ratio. Finally, proteins secondary structure was followed by observing the 1670 cm-1/1650 cm-1 ratio related to β sheets and α helices respectively. Conclusion: UVA dose induced a loosening of the lateral packing of lipids immediately after irradiation. In contrast, the delayed impact was a tightening of the lipid barrier, an increase in the water content and mainly in the unbound water fraction and higher relative amount of β sheets in SC proteins. Put together, these observations can explain the thickening of the SC observed by previous studies. 15 mJ/cm² UVB dose was apparently below the threshold to induce significant changes despite the evolution trends that were obtained in this study.