© 2016 Elsevier Ltd The recently developed crystalline sponge method, which employs single-crystal X-ray diffraction to determine the structure of an analyte present in liquid or oil and having a low melting point, was adopted for measuring methyl salicylate, a time-honored oily medicinal drug. Six independent molecules existed in the asymmetric unit of the crystalline sponge. We succeeded in solving the fine structure of methyl salicylate, which had almost no unassigned fragment and/or solvent in the void spaces constructed by the network complex, and discussed the precise geometry of these molecules. All the methyl salicylate molecules were stacked in layers. By using the crystalline sponge method, the molecular diversity and the related specific homogeneous molecular interactions of methyl salicylate were observed in the lone space in the framework.