We analyse a sample of 12 RS CVn-type systems for which accurate photometry exists, extending from optical to near-infrared and even to IRAS bandpasses in some cases. We reconstruct the energy distribution expected from the binaries, taking into account the radii and spectral types of the components, and we compare them with the observed fluxes. In five cases, an infrared excess (in the range 0.4-1.2 mag) is clearly present. Assuming that this is due to an absorbing shell, we estimate the required mass of dust, which turns out to be in the range 10 −11 -10 −14 M ○. ,corresponding to total shell masses (including gas) in the range 10 −9 -10 −12 M ○. . We suggest that the circumstellar envelopes are built by mass loss in the form of stellar winds driven by magnetic activity