Four-neutrino oscillations and the solar neutrino problem

We perform a fit of solar neutrino data in the framework of the two four-neutrino schemes that are compatible with the results of all neutrino oscillation experiments. These schemes allow simultaneous transitions of solar νeʹs into active νμʹs, ντʹs and sterile νs. The data imply that the SMA solution is valid for any combination of νe→ active and νe→ sterile transitions, whereas the LMA, LOW and VO solutions disappear when νe→νs transitions are dominant.