Flow regimes classify streams according to their hydrological characteristics and influencing factors. As decision making tools flow regimes inform users regarding seasonal flow patterns. Concerning the European Water Framework Directive, which requires a good ecological status of streams, the natural flow regime is an essential river-specific characteristic. As a component of stream classification an extended consideration is of great interest. This thesis aims to analyse the temporal development of Austrian flow regimes based on mean flows. In this context, flow regimes were determined according to a classification approach by Mader et al. (1996), which was developed for Austrian streams. The classification results were compared to the seasonality index. For further investigations, the regime stability, trend, influence of the length of time series and spatial distribution were analysed. Both the determined flow regimes and the results of the seasonality index showed an equal spatial distribution. In the northeast lowland and hilly region especially pluvio-nival regimes with multiple peaks were determined. The Alpine region was characterised by three aspects: Glacial regimes occurred near glaciated regions, while in the northern Alps single peaked nival regimes and in the southern Alps nival regimes with multiple peaks were determined. A high number could not be classified according to the applied classification scheme. The Alpine divide was identified as the strongest spatially separating element. The investigation of the length of the time series showed, that stable results can only be achieved on the basis of long-term observations. The influence of climate change led to more pluvial flow regimes. However, the analysed technique for flow regime classification of Austrian streams in the present form has the disadvantage of limited applicability. Finally some approaches for adaptations are proposed in this work.