We present in this paper an algorithm for determining 3D motion and structure from correspondences of nline segments between two perspective images. To our knowledge, this paper is the first investigation on use of line segments in motion and structure from motion. Classical methods use their geometric abstraction, namely straight lines, but then three images are necessary. We show in this paper that two views are in general sufficient when using line segments. The assumption we use is that two matched line segments contain the projection of a common part of the corresponding line segment in space. Indeed, this is what we use to match line segments between different views. Both synthetic and real data have been used to test the proposed algorithm, and excellent results have been obtained with real data containing about one hundred line segments. The results are comparable with those obtained with calibrated stereo.