Abstract Recently, we have found periodic oscillations of Josephson-vortex flow resistance as a function of in-plane field in Bi 2 Sr 2 CaCu 2 O 8+ y single crystals [Phys. Rev. Lett. 89 (2002) 247002]. This phenomenon was interpreted to arise from a matching effect between the lattice spacing of Josephson vortices and the width of samples. To clarify further for this explanation, and study the effects of the sample boundaries on the Josephson-vortex flow, we have measured the in-plane anisotropy of Josephson-vortex flow resistance. When the field orientation is parallel to boundaries, the flow resistance is strongly suppressed, and the periodic oscillations are clearly observed. This suggests that the effects of sample boundaries are important for the Josephson-vortex flow, especially at the regime of low currents.