The aim of this paper is to study the dominant dimension of two important classes of finite dimensional algebras, namely, hereditary algebras and tree algebras. We derive an explicit formula for the dominant dimension of each class.[21] H. Tachikawa, Quasi-Frobenius Rings and Generalizations QF-3 and QF-1 rings (Notes by C.M. Ringel), Lecture Notes in Mathematics 351,