Dilute mixtures of He3 in liquid He4 are regarded as a set of He3 atoms intereacting with elementary excitations of the He4. The coupling between the He3 and the He4 is chosen phenomenologically and it is not weak but, for low temperatures, its main effects may be eliminated by means of two canonical transformations. The equations which determine the transformations describe the motion of a He4 excitation in the presence of one or two He3 atoms and, in the latter case, they resemble Faddeev's equations in the three-body problem. At low temperatures, there are few He4 excitations and many of the properties of the mixture are determined by the effective He3 Hamiltonian produced by the transformation. In this respect, the system behaves like a Fermi liquid. The He3-He3 potential is essentially momentum-independent and consists of the Van der Waals interaction together with an effectively repulsive potential induced by the He4. It is suggested that a Fermi-liquid analysis is the best way of obtaining information about this potential, and the possible existence of a fermion superfluid phase transition is discussed from that point of view.