<p>This study explores the influence of printing orientation on the tensile mechanical properties of polyamide 12 (PA12) fabricated using the selective laser sintering (SLS) process, more precisely the study of the sensitivity of Young’s modulus and ultimate tensile strength to variations in printing orientation. Tensile tests are conducted on specimens printed at 0°, 45°, and 90° angles in accordance with the ISO 527-2 1BA standard. These tests clearly showed that the Young’s modulus and tensile strength of the specimens printed at 0° are the highest. (For Young’s modulus, we have noted − 5.56% for 45° and − 9.33% for 90° compared to the specimens printed at 0°, and for ultimate tensile strength, we recorded − 6.22 and − 12.16% for 45° and 90°, respectively, compared to the specimens printed at 0°.) To complement experimental investigations, a finite element model was developed in Ansys APDL, integrating the Gurson–Tvergaard–Needleman (GTN) and Chaboche models to account for material porosity. The agreement between the numerical results and the experimental results demonstrates the validity of the models used to describe the tensile mechanical behavior of the sintered material. Microstructural analysis using scanning electron microscopy (SEM) made it possible to see the distribution of porosities in the specimens and to estimate their rates according to the printing orientation. We observed that the printing direction is related to the distribution and porosity rate. We found that the sample printed at 0° exhibited lower porosity than the specimens printed at 45° and 90° on all surfaces analyzed. All the results found show clearly the influence of printing orientation and then the porosity rate on the tensile mechanical performance of PA12 manufactured by SLS, while validating the predictive numerical model of behavior.</p>