Floods are the largest and most frequent natural hazard in Slovakia; they threaten a relatively large portion of the population. The scope and depth of vulnerability in some population groups due to floods pose a significant societal issue. This is particularly problematic for marginalised Roma communities (MRCs) living in environmentally unstable areas that repeatedly flood. Due to their low social and economic status and multiple disadvantages, these communities experience various forms and types of vulnerability. This paper responds to the adverse situation faced by a large part of this ethnic group by measuring and evaluating the social vulnerability (SV) of MRCs in selected municipalities threatened by repeated floods, with a particular focus on the Spišská Nová Ves district. This study sought to understand the differentiated level of SV, identify high-risk municipalities in terms of SV, determine the specific prevailing type of vulnerability, and confirm or refute the existence of a dependency between SV level and the proportion of Roma in the examined municipalities. Results confirmed the hypothesis that the most vulnerable municipalities have the highest proportions of marginalised Roma in their populations. The correlation coefficient showed a strong linear correlation between the level of SV and the proportion of the Roma population in the examined municipalities. All information obtained on the SV of Roma communities (level, risk, nature, specific vulnerabilities, conditions and causes) is a valuable source for assessing flood risks for the Roma ethnic group in Slovakia. The approach used to study the SV of MRCs is applicable to various marginalised groups and other natural risks; it can be generalised across geographic scales, analytical frameworks, different natural hazards, and index-creation methods.