Stevioside is a naturally occurring diterpenoid glycoside in Stevia rebaudiana Bertoni. The title compound, C38H60O18·4CH3OH, crystallized as its methanol tetrasolvate. Stevioside consists of an aglycone steviol (a tetra-cyclic diterpene in which the four-fused-ring system consists of three six-membered rings and one five-membered ring) and a sugar part (three glucose units). A weak intra-molecular O-H⋯O hydrogen bond occurs. In the crystal, the methanol mol-ecules participate in a two-dimensional hydrogen-bonded network parallel to b axis with the sugars and together they form a hydrophilic tunnel which encloses the lipophilic part of the molecule.