The two magnetic compounds Ce 2Sn 5 and Ce 3Sn 7 have very similar crystallographic structures. They are both superstructures of CeSn 3 with two different cerium sites: one, similar to the cerium site in CeSn 3, is “non-magnetic” or in intermediate valence state, and the other carries a well-defined moment and dominates the magnetic properties at low temperatures. Although their macroscopic magnetic properties under the effect of an applied field look quite similar, the magnetic structures of the two compounds in zero field are totally different. In fact, Ce 2Sn 5 presents a modulated structure with moments of maximum value 1.3μ B aligned along a, whereas Ce 3Sn 7 is an antiferromagnet with moments of only 0.36μ B parallel to c. This difference cannot be attributed to different Crystal Electric Field effects, which, from inelastic neutron spectroscopy measurements, are found to be fairly close in the two compounds. A strong anisotropy of the interionic exchange coupling is evidenced in both compounds from the magnetization curves and neutron data, within a crystal field model. Especially, in Ce 3Sn 7, a negative value is found for the c component of the exchange coefficient, leading to strong negative interactions when moments are aligned along c. The effects of hybridization of the cerium 4f-electron with the band electrons play an important role in Ce 2Sn 5 and Ce 3Sn 7. In both compounds, besides the intermediate-valent behavior of cerium in the CeSn 3-type site, Kondo effects are present on the magnetic cerium site, leading to an extra reduction of the cerium magnetic moments. These hybridization effects are also likely to be at the origin of the anisotropy of the exchange interactions and of the resistivity.