The structural effect of trehalose confined in water-containing sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles at water to AOT molar ratio W = 5 and 10 as a function of the trehalose to AOT molar ratio T (0 < T < 0.1) has been investigated by small-angle neutron scattering (SANS). SANS data analysis is consistent with the hypothesis that trehalose is encapsulated within the quite spherical hydrophilic micellar cores of water-containing reversed micelles, causing an increase of the aggregate size and a decrease of the polydispersion. Moreover, SANS results suggest that the trehalose confinement in water-containing reversed micelles involves marked changes on the molecular packing of the water-containing micellar cores. In particular, according to the obtained findings, we can hypothesize the intercalation of the trehalose molecules between the polar surfactant headgroups. The preferential solubilization in this specific nanodomain could explain the trehalose capability to prevent, upon dehydration, the transition to a gel phase, hindering serious damage to biostructures.