A phase diagram of the vortex state of Bi-2212 single crystals in a magnetic field parallel to thec⁁-axis proposed under the assumption on the two-stage destruction of long-range vortex correlation in such crystals matches with the experimental results obtained by using different methods.1234567The intersection of the dimensional crossover lineBcr(T)with the line corresponding to violation of long-range vortex correlations in the(ab&dbgcaret;)-plane makes it possible to explain the discontinuity at the critical point of the vortex lattice melting curveTm(B).Possibilities of experimental investigation of low-temperature condensed state forB>Bcrand the temperature dependenceBcr(T)are considered. ©1998 American Institute of Physics.