We study the electronic transport through moelcular junctions in the weak to intermediate coupling to the leads. In this regime electron-electron interaction plays a crucial role. Another main ingredient necessary to understand transport prperties is the symmetry of the molecule. Taking as starting point a semiempirical model (Pariser-Parr-Pople Hamiltonian) I will show how the electron-electron interaction and symmetry give peculiar fingerprints in the conductance and stability diagrams for different molecules.