Vaslui County is a county (județ) of Romania, in the historical region Western Moldavia, with the seat at Vaslui.

Western Moldavia, also called Romanian Moldavia, or simply just Moldova is the core historic and geographical part of the former Principality of Moldavia situated in eastern and north-eastern Romania. Until its union with Wallachia in 1859, the Principality of Moldavia also included, at various times in its history, the regions of Bessarabia, all of Bukovina, and Hertsa; the larger part of the former is nowadays the independent state of Moldova, while the rest of it, the northern part of Bukovina, and Hertsa form territories of Ukraine.