Complex structural shapes can be produced with additive manufacturing. The geometrical complexity that can be achieved translates into an increase in possible designs. Designing these structures with traditional methods is difficult. A design process with computational optimization will enable engineers to use the geometrical freedom offered by these manufacturing methods. This study explores how topology optimization can be used to design structures that are fatigue tolerant. Two optimization algorithms for fatigue tolerance were developed in this thesis. One algorithm minimizes the stress intensity factor, whereas the other one maximizes the fatigue crack growth life. Both algorithms use a resource constraint to limit the total amount of material, an enriched finite element method to analyze the crack growth performance and the method of moving asymptotes to incrementally improve the design. Example problems showed that the algorithm dramatically improves the fatigue resistance.