Although additive manufacturing of the titanium alloy Ti6Al4V has been an established process for years, problems still exist with regard to the design of components subjected to cyclic loads. In this context, process-related defects play an important role, such as surface roughness and pores. Typically, AM Ti6Al4V components are machined and subjected to a hot isostatic pressure (HIP) treatment, which, however, strongly limits the cost advantage. Mechanical surface treatment processes can be used locally where high loads are expected and thus make a cost-effective contribution to the service life of additively manufactured components. In the present work, the influence of the mechanical surface treatment process of deep rolling (DR) on the surface state of electron beam melted (EBM) and EBM+HIP components is investigated. In addition, rotating bending tests are presented in SN curves and these are evaluated in the context of the surface layer condition and the failure mechanisms. The fatigue strength could be improved from RAB=157MPa in the as built state (AB) to RAB+DR=251MPa in the deep rolled state (AB+DR). Through the deep rolling treatment, the surface could be strengthened to the extent that the location of the failure shifts into the component volume. The comparison of the fracture surfaces analysis of deep rolled samples shows that pores below the surface are the cause of failure, in a depth that is not influenced by the mechanical surface treatment. In an additional series of tests, the fatigue strength of the HIP and deep-rolled (HIP+DR) state was determined. Since HIP EBM specimens are nearly pore-free, the failure mechanism switches back to the strengthened surface, resulting in an increased fatigue limit of RHIP+DR=413MPa.