For lattice chiral and gauge models the authors develop an 1/N² expansion of the mean-field approximation. Special attention is paid to the free energy for which they also present as an 1/N² expansion the effect of fluctuations around the mean-field solution. The differences between U(N) and SU(N) are pointed out. Finally, for the chiral model they apply the mean-field saddle-point technique to compute the two-point correlation function.