This project concentrates on two issues in the theory of fermionic condensates. Firstly, the T-matrix formulation of the pairing theory will be advanced, whereby the particle-particle ladder diagrams in the superfluid state will be summed. Secondly, the phase diagram of asymmetrical superfluids and superconductors will be studied including tensor interactions and deformations of Fermi surfaces. The first problem is aimed at an extension of the T-matrix theory below the critical temperature of superfluid phase transition. The aim is to avoid the divergence of the T-matrix in the normal state and to build a consistent theory beyond the BCS-mean-field model.The second problem will extend our knowledge about the phase diagram of asymmetric superconductors and superfluids to new phases of matter with deformed Fermi surfaces. Applications to nuclear systems, such as spin-polarized neutron matter or isospin asymmetrical nuclear matter as well as ultracold atomic gases will be performed.