The closed set of relativistic hydrodynamical equations describing str
ongly magnetized collisionless plasma with an anisotropic pressure ten
sor is offered. This model is the generalization of Chew-Goldberger-Lo
w [Proc. R. Soc. London Ser. A 236, 112 (1956) ] theory for the relati
vistic case. It is shown that at high temperatures the equation of sta
te differs significantly from the ones used earlier.