Let K/k be a finite purely inseparable extension of field k of characteristic p > 0. A factorization of length m of K/k is the data of m intermediate fields K1,K2, ··· ,Km of K/k such as K ≃ K1 ⊗k K2 ⊗k ···⊗k Km. In the present paper, we are especially interested in the uniqueness of the form of factorizations of maximum length.