In the present work the local stress concept for fatigue life calculation of short fibre reinforced thermoplastic parts is presented closely to application. A great number of static, quasistatic and cyclic fatigue tests, performed on three different types of short glass fibre reinforced thermoplastics, represent the groundwork of the thesis. They serve for basic characterisation of material behaviour and for achieving a meaningful data base. Influences which are particularly relevant for thermoplastic material and cyclic fatigue loading in engine compartment are worked out through deepening material tests additionally. So the influences such as fibre orientation, weld line, elevated temperature, moisture and ambient media are clarified mainly by quasistatic tensile tests. Additional stress controlled fatigue tests in form of S/N curves are used to investigate the impact of these influence factors on fatigue strength. This allows studies of correlation between quasistatic and cyclic material properties. Regarding with respect to well-known effects of cyclically loaded components made of metals also the influences of mean stress and stress concentrations on fatigue strength of short fibre reinforced thermoplastics are characterised. In this connection particular attention is paid to the interaction between the support effect in stress concentrations and an elevated temperature. Strain controlled fatigue tests to investigate the low cycle fatigue (LCF) behaviour form a special part of the thesis. This investigation delivers a deeper insight into cyclic material behaviour by analysing the stress/strain hysteresis and can be considered as a first step towards fatigue life calculation based on local strains. For industrial implementation of the local stress concept in consideration of the manufacturing process mathematical relations are deduced to describe the quasistatic and cyclic material behaviour. Effects of fibre orientation and stress concentration are described by recognised approaches and analysed in terms of their suitability and sensitivity. As an essential contribution to the enlargement of the local stress concept for thermoplastic parts new approaches for characterising influences such as ambient temperature, interaction between support effect of stress concentrations and ambient temperature and influence of coolant in interaction with fibre orientation and ambient temperature are suggested. Also the determination of the cyclic stress/strain behaviour according to Ramberg-Osgood from strain controlled LCF tests gives an improvement for the method.