Abstract : Isotopic effects are studied in reactions induced by 40Ca projectiles at 25 MeV/nucleon on 40Ca, 48Ca, and 46Ti targets. The N/Z contents of projectilelike and midvelocity (MV) sources are probed by means of isotopic (7Li/6Li and 9Be/7Be) and isobaric (7Li/7Be) yield ratios, for semiperipheral events. In particular, information about isospin transport phenomena will be discussed. Isospin diffusion processes involving nuclei, which have noticeable differences in N/Z have been investigated. Signals of isospin drift, which are related to the gradient of density in the participant region, have also been observed for fragments emitted at MV.