We construct the spectral representation of spinor two-point functions in medium, that is, at finite temperature and chemical potential. We first deal with the free spinor two-point function. Then we construct the same for interacting fields leading to the Källen-Lehmann representation. It is emphasised that although these two point functions have the structure of 2 × 2 matrices in the real time formulation of field theory, any one component actually suffices to describe the dynamics of the system. Our construction is then applied to write the QCD sum rules for two-point function of nucleon currents in medium. We discuss a subtracted version to increase the sensitivity of such a sum rule and point out how it differs from a conventional one.