We investigate higher variations of Lagrangians in the framework of finite order variational sequences. In particular we obtain explicit expressions for second variations that are naturally related to the geometric structure of the problem. We recover the definition of the Jacobi morphism and of the Hessian at an arbitrary order, and show the relation between them. We investigate the relation between Jacobi fields, symmetries of higher variations and conserved currents; we show that a pair given by a symmetry of the l-th variation of a Lagrangian and by a Jacobi field of the s-th variation of the same Lagrangian (with s < l) is associated with a (strongly) conserved current. Furthermore we prove that a pair of Jacobi fields always generates a (weakly) conserved current. The example of the Jacobi equation for a Yang-Mills theory on a Minkowskian background is worked out and the current associated with two Jacobi fields is obtained in this case.