  The precise measurements of vortex melting point towards a need to develop a
quantitative theoretical description of thermal fluctuations in vortex matter.
To tackle the difficult problem of melting, the description of both the solid
and the liquid phase should reach the precision level well below 0.1%. Such a
theory in the framework of the Ginzburg - Landau approach is presented. The
melting line location is determined and magnetization, specific heat jumps
along it are calculated. We find that the magnetization in the liquid is larger
than that in the solid by 1.8% regardless of the melting temperature, while the
specific heat jump is about 6% and slowly decreases with temperature. The
magnetization curves agree with experimental results on $YBCO$ and Monte Carlo
simulations.
