[en] A variational theory of the BCS pair-condensed state of strongly interacting Fermi systems is presented. The short-ranged correlations among the particles are described by a correlation operator which induces state-independent correlations of the Jastrow type. The two-body distribution function and the one- and two-body density matrices are expanded to all orders of the dynamical correlations and of the BCS amplitudes, and are expressed in terms of irreducible quantities. A Fermi hypernetted chain (FHNC) technique is derived to sum up all the terms of the corresponding series. (orig.)