The evolution of the crystal structure and some magnetic properties of the heavy-fermion materialCeCu6 − xSnx (x = 0, 0.25, 0.65, 0.75, 0.85 and 1.0) has been studied by powder neutron diffractionand by specific heat measurements. The substitution of Cu by Sn suppresses thetemperature induced orthorhombic to monoclinic transition, known to occur in the pureCeCu6 phase. No structural phase transition has been observed in these samples as a function ofx but the cell volume increases considerably in an anisotropic way. Sn occupies preferentiallythe special Cu crystallographic site which is next to each of the four Ce atoms in the unitcell. The transition to antiferromagnetic order, characterizing the samples with higherx, is sensitiveto both x and magnetic field. The results are discussed in the context of the competition betweenKondo and RKKY interactions in disordered or not heavy-fermion systems andreveal an interesting interplay between composition, structure and magnetism inCeCu6 − xSnx.