Selective Laser Melting (SLM) is a method of additive manufacturing (AM), which builds metal parts in a layer by layer procedure based on a CAD template. The cross section of the CAD part is melted into the respective layer. The melting of metal powder by an energy beam and successful mastering of the whole manufacturing procedure requires complex management, because multitudes of variables enter the SLM process. These variables are laser power, scan speed, thickness of layer, overlap rate and building direction. This article summarizes their impact on tensile properties and structure of printing materials. An important finding of the investigation follows. The SLM built steel samples usually have better tensile properties than those conventionally manufactured providing the additive manufacturing is properly managed.