One of the main issues in geotehnical engineering is the slope stability. In order to remediate landslides, the causes that led to the instability must be determined, and one of the most common natural causes of landslides is the precipitation. The subject of this dissertation is focused on the numerical modeling of the slope caused by precipitation of different intensity and duration, and examination of the effect of each of the events on the stability of the slope. The numerical model has been implemented on the basis of the data on the existing landslide in the Veliki Vrh street in the area of the City of Zagreb, where the landslide occurred at the beginning of April 2014. This paper presents firstly the basic theoretical background knowledge required for understanding the process of water flow in the soil, and the introduction to the numerical modeling with emphasis on the software used to produce the simulation. Moreover, the geological situation and the engineering-geological properties of the materials needed for model setup, as well as the analysis of the rainfall quantity that had preceded the creation of landslide are presented. Numerical modeling has been performed in three stages. In the first stage, the primary model with the initial groundwater level has been established. Subsequently, low intensity precipitation in a 7-months period has been modeled, and finally a high-intensity rainfall event of the duration of 4 days has been simulated. In the final part, the analysis has been carried out and the results of the numerical modeling have been compared, thus showing which rainfall event is more critical for the slope stability.