This paper investigates the microstructure, high cycle fatigue (HCF), and fracture behavior of additive manufactured AlSi10Mg samples using Selective Laser Melting (SLM). The samples were manufactured by a powder-bed process and machined after fabrication. Nine samples were produced without and with heating of the building platform at 30°C and 300°C, and in different directions (0°, 45°, 90°). The samples were tested in the peak-hardened (T6) and as-built conditions. The Wöhler curves were interpolated using a Weibull distribution, and the results were analyzed statistically through design of experiments, correlation analysis, and marginal means plots. The study found that post-heat treatment had the most significant effect on fatigue resistance, while the building direction had the least significant effect. The fatigue resistance of the samples was high compared to the standard DIN EN 1706. The combination of 300°C platform heating and peak-hardening was found to be an effective approach to increase fatigue resistance and neutralize differences in fatigue life for the 0°, 45°, and 90° directions. The microstructure of the samples was characterized by cellular dendrites of α-Al and interdendritic Si particles. Peak-hardening homogenized the microstructure, eliminated microstructural differences, and reduced crack initiation and propagation, thereby increasing fatigue resistance. The 300°C platform heating reduced imperfections and residual stresses, contributing to higher fatigue resistance. The study concludes that the combination of 300°C platform heating and peak-hardening is a valuable approach to enhance fatigue resistance and static tensile strength, and that process parameters need to be improved to increase current density and avoid imperfections. Despite porosity and imperfections, the fatigue resistance of the samples is very high compared to the standard DIN EN 1706.This paper investigates the microstructure, high cycle fatigue (HCF), and fracture behavior of additive manufactured AlSi10Mg samples using Selective Laser Melting (SLM). The samples were manufactured by a powder-bed process and machined after fabrication. Nine samples were produced without and with heating of the building platform at 30°C and 300°C, and in different directions (0°, 45°, 90°). The samples were tested in the peak-hardened (T6) and as-built conditions. The Wöhler curves were interpolated using a Weibull distribution, and the results were analyzed statistically through design of experiments, correlation analysis, and marginal means plots. The study found that post-heat treatment had the most significant effect on fatigue resistance, while the building direction had the least significant effect. The fatigue resistance of the samples was high compared to the standard DIN EN 1706. The combination of 300°C platform heating and peak-hardening was found to be an effective approach to increase fatigue resistance and neutralize differences in fatigue life for the 0°, 45°, and 90° directions. The microstructure of the samples was characterized by cellular dendrites of α-Al and interdendritic Si particles. Peak-hardening homogenized the microstructure, eliminated microstructural differences, and reduced crack initiation and propagation, thereby increasing fatigue resistance. The 300°C platform heating reduced imperfections and residual stresses, contributing to higher fatigue resistance. The study concludes that the combination of 300°C platform heating and peak-hardening is a valuable approach to enhance fatigue resistance and static tensile strength, and that process parameters need to be improved to increase current density and avoid imperfections. Despite porosity and imperfections, the fatigue resistance of the samples is very high compared to the standard DIN EN 1706.