Weld Lines (WLs) occurrence in injection-molded thermoplastic parts is often unavoidable and induces a significant reduction in the mechanical properties, especially for short fiber-reinforced materials. The effect of WLs on the mechanical properties of reinforced thermoplastics has been extensively studied [1, 2], but the prediction of the mechanical properties in the vicinity of the WLs is still a challenging task. In this work we present a mechanical characterization of the WLs induced in injection-molded 30 wt% glass fiber-reinforced PBT, which constitutes the experimental reference for validating the respective prediction models. We considered frontal and flowing WLs by using different insert shapes, different flow types (parallel and divergent) and two thicknesses (1.5 and 3.0 mm). We also studied the effect of the process parameters, in particular melt and mold temperatures, packing pressure and injection speed on the mechanical properties of the WL. We found that the influence of the process parameters and the insert shape (in the case of flowing WLs) on the quasi-static tensile properties of the WL is relatively low. Also we found that frontal WLs induce a more pronounced reduction of the tensile strength in comparison with the flowing WLs. Based on rheological tests performed on the unreinforced PBT matrix, we determined that the healing ability of the matrix at the WL is high. On the other hand we observed that the unfavorable induced Fiber Orientation (FO) along the flowing WL does not vanish with the distance from the insert. The last results suggest that the FO is the dominant factor of the WL strength reduction, while matrix inter-diffusion does not play a significant role. Keywords: weld line, injection molding, short fiber-reinforced thermoplastics, tensile strength [1] Meddad, A., Fisa, B., Polymer Engineering & Science, 35 (11), pp. 893-901 (1995). [2] Nadkarni, V.M., Ayodhya, S.R., Polymer Engineering & Science