The morphometric analysis of alluvial drainage provides insights into its dynamics, erosion capacity, susceptibility to floods and possible genetic relations to tectonic faulting. In this study, we analysed the drainage system of Samos Island, located in the northern Aegean Sea. The results indicate a vulnerability to erosion and flooding events, and these intense phenomena concentrate mostly on third-order catchments. Two dissimilar drainage network systems are shown: an older drainage network system with a main NW–SE direction, which includes fourth- and fifth-order branches, and a recent drainage network system, which includes new, smaller order branches with a main NE–SW direction. The major tectonic fault orientations are NNW–SSE. The branches of the hydrographic network and faults present different directions, which indicates that the hydrographic pattern is not affected by tectonics.