We investigate theoretically the technologically essential Auger recombination lifetime in narrow-gap semiconductor superlattices by means of a completely first-principles formalism, based on accurate energy bands and wave functions provided by the full-potential linearized augmented plane wave scheme. The minority carrier Auger lifetimes are determined by two correlated approaches: (1) direct evaluation in Fermi's golden rule, and (2) indirect evaluation, based on a detailed balance formulation relating Auger recombination and its inverse process, impact ionization, in a unified framework. Lifetimes determined by the direct and indirect methods for n -doped HgTe/CdTe and InAs/InxGa1－xSb superlattices exhibit excellent consistency with experimentally measured values. This justifies the computational formalism as a new sensitive tool in performance optimization of the synthetic narrow-gap semiconductor superlattice systems.