Distributional relationships among closely related taxa can provide key information about the levels of their reproductive isolation or compatibility, and thus the stage of speciation process. Here, we present new information on the sites where two taxa traditionally considered as subspecies of the Subalpine Warbler Sylvia cantillans, S. c. cantillans and S. (c.) moltonii, breed sympatrically in mainland Italy. We analyse geographic distribution and behaviour as well as other characteristics shown by these warblers in the areas of contact. The distributional pattern shown by these taxa, which is partly sympatric with syntopic breeding, and the apparent lack of interbreeding, strongly suggest that they behave as different species, confirming previous findings about genetic divergence and differential song perception.