[en] A three-dimensional ray-tracing code for the stellarator plasma is worked out. By an integration along its trace the ECE line profiles at the second harmonic for different W VII-A plasma parameters are calculated. Attention is paid especially to which line profile should be recorded by the diagnostics, the influence of the finite aperture of the antenna, the wave polarization and wall reflection are studied. The reliability of measuring temperature profiles by ECE line shape is discussed. The code can be used to calculate the expected ECE spectrum. (orig.)