The variability in mechanical properties in selective laser melted (SLM) maraging steel parts was captured by testing miniature size tensile coupons that were extracted from different locations in the part. Tensile testing provides better mechanical response to defects such as pores and inclusions as compared to hardness testing. The effect of heat treatment on the tensile property variation with different section thickness was also studied. It was observed that tensile property of miniature samples was more sensitive to porosity defects in maraging steel samples. The elongation values in the tensile specimens exhibited more variability as the section thickness of the part was reduced. This was due to the presence of more pore defects in thin wall sections. Heat treatment did not influence the tensile properties with respect to the wall thickness except for an increase in the strength due to hardening.