The heterogeneity of the regional leaf beetle fauna from Galicia in northwestern Spain is analyzed to determine the influence of Eurosiberian-Mediterranean boundary on Chrysomelidae assemblages. We compared eight local faunas from both sides of the phytogeographic boundary between Eurosiberian and Mediterranean regions, taking into account the species richness and completeness of each inventory, its composition of zoogeographic chorotypes, and beta diversity between areas. The selected areas were coastal dunes and associated marshes, agricultural landscape near Santiago de Compostela, Atlantic mixed forest of low altitude in Fragas del Eume Natural Park, medium-altitude mountain ranges of Dorsal Gallega and Larouco, the temperate valley of the Sil River and high mountain ranges of Ancares and Eixo-Segundera. Simpson’s index (β_sim) was selected as beta diversity measure, to avoid the effect of richness gradients and thus minimize the bias produced by the uneven sampling effort. A nonmetric multidimensional scaling (NMDS) based on β_sim was performed to ordinate the local faunas, and a cluster analysis using the dimensions values for each inventory was used to recover the major faunistic groups. The Sil Valley is strongly discriminated from all other inventories by the NMDS and the cluster analysis and presents a ratio between Mediterranean and Eurosiberian elements markedly higher than the remaining areas. Among the latter, two other groups are recovered: the southern and eastern mountain ranges located near both sides of Eurosiberian-Mediterranean phytogeographic boundary, and the low- and medium-altitude areas closer to the Atlantic coast. Therefore, zoogeographic distributions of leaf beetle faunas in northwestern Spain do not fit exactly the standard phytogeographic zonation, because only the Sil Valley is found to have a distinct Mediterranean-type fauna, whereas Galician mountain ranges included in the phytogeographic Mediterranean region are clustered with Eurosiberian inventories.