Selective laser melting (SLM) is an additive manufacturing (AM) technology proven to produce near fully dense components made of a wide number of materials and with the required printing resolution to manufacture structures with microscopic structural details. Because of complexity of the processing and tensile and fatigue relationships, SLM requires more investigation. For instance, the shielding gas flow (argon flow) has affected the stability of the process and consequently the quality of AM components. In addition to provide an inert atmosphere during the printing process, the argon flow removes process byproducts, such as spatter and smoke that occur during the SLM. Inefficient argon flow results in the interaction of the laser beam with the by-products, leading to the redeposition of these onto the melt pool. This has a negative impact on the surface morphology, density of the parts, and ultimately mechanical performance. In this study we investigated two argon flows (optimized vs. nonoptimized) and their effects on the tensile properties and surface finish of Ti-6Al-4V samples (stress relieved) with different size dimensions and printing directions (horizontal vs. vertical). For the nonoptimized argon flow, we found tensile properties that ranged from 826 to 1,052 MPa ultimate tensile strength (UTS), 925 to 966 MPa yield strength (YS), and 0.6–17% elongation (Elong.). The optimized flow exhibited more consistent results, as follows: 998–1,039 MPa UTS, 878–940 MPa YS, and 15–17% Elong. No statistical difference was found on the average surface roughness for samples printed in the vertical direction (7.26 μm Ra, and 47.90 μm Rz), regardless of the argon flow used. For the horizontal direction, however, the optimized flow showed a smoother surface finish (6.48 μm Ra, 39.46 μm Rz) compared with the nonoptimized flow (11.72 μm Ra, 71.13 μm Rz). The effects of argon flow on density and metallurgical characteristics of printed parts also were discussed.