  We investigate the time-of-night variation of solar neutrino rate which will
be of relevance to Super-Kamioka and Sudbury neutrino detectors in the
framework of oscillations among the three flavors. An analytical method of
computing the regeneration in the earth is presented. If day-night effect is
seen, we show how the study of the time-of-night variation will allow the
determination of the neutrino parameters.
