Dolines were analysed on the basis of a digital relief model with a resolution of 5×5 m. The morphological parameters of the dolines were recorded, and a morphometric analysis of the doline polygons and point pattern analysis of the dolines were performed using GIS. The edges of the dolines were extracted using a semi-automatic method. A total of 34 476 dolines were found in the area of the Istrian peninsula and 17 478 in the area of the Southwestern Istrian Planation Surface. Based on the analysis of lithostratigraphic units and morphometric parameters of the relief, the extent of the Planation Surface was determined. In the area of the Planation Surface, most of the dolines are circular and on average 5,7 m deep. The doline density is 10,02 dolines/km2, and the pitting index 14,33. Most of the dolines are formed in limestones and dolomites of the Lower Cretaceous and in rudist limestones. The areas with the highest doline density are located at altitudes above 200 m above sea level. Digital relief models of different resolutions were compared in the analysis of doline density and slope as well as in doline density and relative relief. The dispersion measure was analysed on several levels. The results of the manual digitisation and the semi-automatic method were compared.