The peculiarities of electrodynamics of layered HTS materials in a longitudinal magnetic field, which are associated with fluctuations of the shape of an Abrikosov vortex formed by a set of weakly coupled2d-vortices centered in equilibrium in superconducting planes, are studied. The value of the longitudinal critical current of the layered media is estimated, and its temperature dependence is determined. ©1997 American Institute of Physics.