Sub-leading 1-2 effects in Atmospheric Neutrinos

In this talk we discuss the implications that a non-vanishing value of Δm212, as indicated by present solar and KamLAND data, has on the analysis of present and future atmospheric neutrino data. This talk is based on the work presented in Ref. [M.C. Gonzalez-Garcia, M. Maltoni, A.Yu. Smirnov, Phys. Rev. D 70 (2004) 093005].