  We perform an updated phenomenological analysis of the
Mikheyev-Smirnov-Wolfenstein (MSW) solutions of the solar neutrino problem,
assuming oscillations between two and three neutrino families. The analysis
includes the total rates of the Homestake, SAGE, GALLEX, Kamiokande and
Super-Kamiokande experiments, as well as the day-night asymmetry and the 18-bin
energy spectrum of Super-Kamiokande. Solutions are found at several values of
the theta_{13} mixing angle. Among the most interesting features, we find that
solar neutrino data alone put the constraint theta_{13} < 55--59 deg at 95%
C.L., and that a fraction of the MSW solutions extends at and beyond maximal
(nu_1,nu_2) mixing (theta_{12} > pi/4), especially if the neutrino square mass
splitting is in its lower range (m^2_2-m^2_1 ~ 10^{-7} eV^2) and if theta_{13}
is nonzero. In particular, bimaximal (or nearly bimaximal) mixing is possible
for atmospheric and MSW solar neutrino oscillations within the stringent
reactor bounds on theta_{13}.
