The mode conversion of symmetric into antisymmetric Lamb waves in non-damaged CFRP plates caused by their inhomogeneity is discussed. Lamb waves in differently stacked CFRP plates are observed via scanning laser vibrometry. In addition to the dominating wave crests observed propagating through the plates, as predictable from a macro-mechanical point of view, different patterns of parallel lines occur. These are analyzed and classified into three effects: Mode conversion at micro scale (fibers) and a static bending-stretching coupling effect at meso scale (weave rovings), also causing mode conversion under additional conditions. To consolidate the findings, tensile tests are performed and observed with a 3D image correlation method and a volume FE model of a twill fabric woven layer is used for static as well as dynamic simulations. The numerical results and the experimental data show a good agreement.