Nowadays, making use of additive manufacturing (AM) processes such as fused deposition modeling (FDM), in different areas, such as car manufacturing, biomedical and aerospace industries is gaining popularity worldwide because of their capacities in producing functional parts with complex geometries. Therefore, it is very important to identify the significance of FDM processing parameters which would have an impact on the quality of articles produced by the processing system. In this work, poly(lactic acid) was used to study the effects of processing parameters such as layer thickness, raster angle and printing plane on the tensile properties and surface roughness of the printed specimens. The results showed that the tensile strength of a specimen increased by reducing its layer thickness. However, the elastic modulus values increased with decreasing the layer thickness to some extent. Moreover, when the layer thickness was kept constant at 0.05 mm and 3D-printing was carried out in XYZ plane, the maximum modulus and tensile strength were obtained for the raster angle of 0˚. Microscopic studies showed that in low layer thickness, the polymeric layers diffused properly into each other and no voids were formed between the layers. However, with a thickness above its critical value, a few voids were formed between the layers which played as a stress concentrator and decreased the tensile strength of the specimens. The results also showed that the surface roughness increased with increasing the layer thickness.