The statistical terpolymer composed of 52 mol% vinylidene fluoride (VDF), 36 mol% tetrafluoroethylene (TFE) and 12 mol% hexafluoropropylene (HFP) is a ductile material that can be highly deformed in uniaxial tensile tests. Wide-angle and small-angle X-ray scattering (WAXS, SAXS) techniques have been used to study the structure of uniaxially oriented samples. WAXS shows that the terpolymer exhibits a low degree of crystallinity (x(c) approximate to 0.1). The crystalline structure combines features of both VDF and TFE, in agreement with previous studies on VDF/TFE copolymers. Concentration fluctuations do not contribute significantly to SAXS of the VDF/TFE/HFP melt. Melt-crystallized samples exhibit a lamellar morphology with a long period of L = 12 nm and a volume fraction of crystallites of Phi(c) = 0.26. Deformation of the terpolymer at T = 50 degrees C results in a four-point SAXS pattern, which gradually changes to a two-point pattern when the drawing temperature increases. The mean-square fluctuation of the electron density strongly decreases at low drawing temperatures. It is assumed that vacancies introduced near the grain boundaries reduce the density of the crystalline layers.