The assessment of river flood vulnerability requires analysis of the whole physical-geographical environment, and taking into account the interaction between all natural and social–economic components of the study area. In the current paper a flood vulnerability map is elaborated in Geographical Information Systems (GIS) environment using fuzzy logic overlay analysis. Precipitation, distance from streams, flow accumulation, lithology, land use, slopes and altitude are considered and analysed as factors influencing the floods. In particular, the proposed methodology for an assessment of flood vulnerability by fuzzy logic is applied for the catchment of the river Luda Kamchia. This river is situated in the Eastern Bulgaria, Europa. It takes about 1600 km2. The relief is mainly low-mountainous and the annual amount of precipitation is between 600 and 800 mm, influenced by the Black sea in the eastern part of the river basin. Proposed methodology for the assessment of river flood vulnerability and elaboration of maps of flood vulnerability by fuzzy logic overlay analysis in GIS environment is a first step in development of the information system for integrated risk assessment from natural disasters.