  The modified versions of the bag model equation of state (EoS) are
considered. They are constructed to satisfy the main qualitative features
observed for the quark-gluon plasma EoS in the lattice QCD calculations. A
quantitative comparison with the lattice results at high temperatures T are
done in the SU(3) gluodynamics and in the full QCD with dynamical quarks. Our
analysis advocates a negative value of the bag constant B.
