In an optical coherence tomography system for the examination of human or animal tissue or organs, a catheter is insertable into the tissue or organ to introduce light into the tissue or organ and the reflection is transmitted to an evaluation unit, where the reflection and a reference light are evaluated interferometrically to determine a two-dimensional cross-sectional view of the tissue or organ. At least one position sensor is at the tip of the catheter, and a position-determining system derives position data describing the current position of the position sensor in the coordinate system of the position-determining system. The position-determining system also captures position data regarding the spatial position of the cross-sectional views in the same coordinate system and the evaluation system derives a three-dimensional view from several of the cross-sectional views and the corresponding position data.