Let E be an elliptic curve defined over Q, let p be a prime number, and let n ≥ 1. It is well-known that the p n-th division field Q(E[p n ]) of the elliptic curve E contains all the p n-th roots of unity. It follows that the Galois extension Q(E[p n ])/Q is ramified above p, and the ramification index e(p, Q(E[p n ])/Q) of any prime ℘ of Q(E[p n ]) lying above p is divisible by ϕ(p n). The goal of this article is to construct elliptic curves E/Q such that e(p, Q(E[p n ])/Q) is precisely ϕ(p n), and such that the Galois group of Q(E[p n ])/Q is as large as possible, i.e., isomorphic to GL(2, Z/p n Z).