Abstract: Argutone——a new constituent having bacteriostatic and sedative activities was isolated from the foliage of the Incarvillea arguta (Royle) Royle. Its structure was evidenced by UV IR ¹H-NMR ¹³C-NMR MS and X-ray diffraction etc as 2-ethoxymethylene-3,5-dihydroxy-γ-pyrone. Both of pyrane ring and two side chain hydroxy groups (C₃-OH, C₅-OH) form a plane structure, and side chain -CH₂OCH₂CH₃ with folding form extends toward a vertical position from this plane. It has weak intra-molecular hydrogen bond and the molecules are held together by Van Der Waals force in the solid state.