Recent publications on the Monte-Carlo simulation of vortex systems in HTS are reviewed. Dependences of the main parameters of the vortex state (such as energy, heat capacity, thermal motion, and structural order parameter) on extrinsic parameters (temperature and magnetic field) are described. The vortex glass phase, the influence of defects on phase diagrams, as well as the main phase transitions in two- and three-dimensional vortex structures including melting and2D-3Dtransition are considered. ©1997 American Institute of Physics.