Due to the increasing demands on lightweight design, the automotive industry is pushed to a continuous advancement of aluminium cast drive train components. Main influencing factor for the local material properties and fatigue strength are the local microporosity and micropore sizes. The aim of this thesis is to investigate microstructural and technological influences on the fatigue strength behaviour of cast aluminium alloys. Two components types, crankcases and cylinder heads, with different aluminium alloy specifications as well as varying heat treatments and eutectic modifiers are researched. Extensive X-ray computed tomography analyses are performed to statistically characterize the basic size distributions of micropores within parameter studies. Thereby it is shown that the General extreme value distribution and the Lognormal distribution correlate well to the resulting micropore size distributions of the measurements. Fatigue tests of the different alloy specifications reveal a distinctive correlation whereby the fatigue strength is reduced with increasing micropore sizes. In the course of a fatigue strength assessment Kitagawa-Takahashi-, El-Haddad- and Chapetti-fatigue life models are set-up. These concepts combine the results of the fatigue and fracture mechanical tests with the fractographic analyses. Thereby, the fatigue assessment model by Chapetti leads to conservative, but well applicable results compared to the testing data. The Kitagawa-Takahashi-model is none-conservative over all investigated data as well as most regions of the El- Haddad models. Hence, a consideration of the short crack propagation region, as incorporated within the Chapetti method, is essential to accurately assess the fatigue strength behaviour of the investigated data sets. In conclusion, the main influence on fatigue resistance, despite differences in heat treatment, alloy specifications and eutectic modifiers, is defined as the micropore size.