This present study focuses on evaluation of mechanical properties of three dimensional (3D)-printed carbon fiber/polylactic acid (CF/PLA) composites, using fused deposition modeling (FDM) technique. The composites were prepared with different slicing parameters: layer heights or thicknesses, infill densities and layer patterns. The 3D-printed composite samples were subjected to tensile, flexural and interlaminar shear strength (ILSS) tests to assess the influence of the process parameters on their mechanical characteristics. Further investigations were carried out to evaluate the effect of surface roughness of the samples. From the test results, it was evident that both rectilinear and hexagonal layer patterns exhibited better mechanical properties at infill density and layer thickness of 60% and 0.64 mm, respectively. The scanning electron microscopy (SEM) images depicted that lesser layer thickness produced poor CF/PLA interfacial bonding and major failure mode was traced to fiber pull-out. Therefore, engineering application of the composite samples depends on their slicing parameters.