  It has been shown that there is a possible mass-period correlation for
extrasolar planets from the current observational data and this correlation is,
in fact, related to the absence of massive close-in planets, which are strongly
influenced by the tidal interaction with the central star. We confirm that the
model in P\"atzold & Rauer (2002) is a good approximation for the explanation
of the absence of massive close-in planets. We thus further determine the
minimum possible semimajor axis for these planets to be detected during their
lifetime and also study their migration time scale at different semimajor axes
by the calculations of tidal interaction. We conclude that the mass-period
correlation at the time when these planets were just formed was less tight than
it is now observed if these orbital migrations are taken into account.
