This master’s thesis presents the definition of new thresholds for rainfall-induced shallow landslides in Slovenia using different methods. The thresholds are basic input data for the early warning systems. Validation of the models, that are currently in use in the Slovenian early warning system MASPREM, showed significant number of missed alarms for eastern Slovenia (especially for Posavsko hills, Koroška etc.), due to thresholds set too high. Based on empirical methods, using analyses of antecedent rainfall and hourly rainfall data for mean and peak intensities of the rainfall events, new thresholds were defined for the area of Posavsko hills. The effect of the lithology on shallow landslides was also researched. The results showed, that the landslides in Posavsko hills occurred at lower amounts of rainfall (35-45 mm in a matter of 1 to 3 days) than previously defined, which is probably the consequence of the lithological characteristics of the area. Most of the landslides (more than 80%) occurred on unconsolidated sediments and sedimentary rocks of different age. In collaboration with experts from the Italian national research center in Perugia (CNR IRPI) new thresholds were also defined with the use of the tool CTRL-T for the whole area of Slovenia. The algorithm is based on statistical analysis of hourly rainfall data and documented spatio-temporal occurrences of landslides, which then defines the most probable rainfall events, responsible for the slope failures. The best result is the threshold with 15% non-exceedance probability, which means that 15% of slope failures occurred bellow the threshold, i.e. at lower amounts of rainfall, probably as a result of human impact on slope stability.