A relevant percentage of the world population lives in constructions made of sun-dried earth, which are built according to several techniques such as rammed earth, bahareque or adobe. This work specifically focuses on the adobe buildings located in the Historic Centre of Cuenca (Ecuador), recognized as a World Heritage Site since 1999. Although these buildings are characterized by different geometrical and material configurations, all of them have load-bearing façade walls made of adobe. This paper illustrates an analysis of the seismic vulnerability of these adobe façade walls according to different geometrical configurations and considering an out-of-plane loading. This study is based on original in-situ collected data about 45 one and multi-storey buildings. The seismic behaviour of the case studies is investigated through a demand versus capacity analysis based on 5 different failure mechanisms and considering a variable intensity of the seismic action. This procedure has allowed to classify the case studies according to their seismic vulnerability and to identify the most relevant failure mechanisms in such adobe façades. As a main result, some continued fragility curves have been produced to allow replicating this procedure to buildings with similar features. Finally, a repair cost estimation after seismic scenarios is estimated.