Currently, additive manufacturing (AM) is not limited to prototype manufacturing, but is also used to generate parts with final applications. This paper considers this aspect of 3D printing, and aims to characterize fatigue life of parts manufactured through fused filament fabrication. This is one of the most complex AM technologies, due to the high number of parameters that must be taken into account. The knowledge of the influence of the different manufacturing parameters on the mechanical behavior of the parts has been previously considered for static forces, but so far, dynamic working regimes have not been explored. In this paper, a design of experiments through Taguchi orthogonal arrays is applied to analyze the influence of five factors on fatigue life on PLA specimens. Five fatigue tests are performed for each combination of parameters. Results show that fill density, nozzle diameter and layer height are the most influential factors on fatigue lifespan. Finally, honeycomb proves to be the most beneficial infill pattern with regards to fatigue life.