Recent observations from the Freja and FAST satellites as well as earlier observations from OGO 5, Heos 2, and DE 2 indicate the presence of fine structures in the field-aligned plasma flows. We have simulated the effects of such structures on ionospheric plasma transport processes, using our three-dimensional large-scale, multimoment, multifluid model. The model solves the continuity, momentum and double adiabatic energy equations with anisotropic ion temperatures in the field line coordinates from 1500 km to 10 RE. It includes important physics of the ionosphere-magnetosphere coupling region, such as the mirror force and generalized ambipolar electric field in a dipole magnetic field geometry. Freja satellite observations of the structured field-aligned currents were used as input parameters in the simulation. It has been shown that in the presence of the field-aligned current filaments with sufficiently small transverse scale sizes, the transverse transport can play a dominant role in the overall plasma response processes in the ionosphere-magnetosphere coupling region. For example, the local changes in parallel flow velocity due to transverse transport, 1 min after the structured field-aligned current application, may be >30%. The plasma response time due to transverse transport has been found to be shorter than that due to parallel transport. The difference is more pronounced at higher altitudes. ¿ 1999 American Geophysical Union