Bagnoli del Trigno is a comune (municipality) in the Province of Isernia in the Italian region Molise, located about 25 kilometres (16 mi) northwest of Campobasso and about 20 kilometres (12 mi) northeast of Isernia. As of 31 December 2004, it had a population of 841 and an area of 36.7 square kilometres (14.2 sq mi).