We present computer simulation results for the effective conductivities of random dispersions of cylinders of arbitrary conductivity relative to that of the matrix phase. The cylinders are randomly positioned in space with their axes parallel to a line, parallel to a plane, or without preferred orientation. Effective conductivities are computed from the mean square displacement of carriers traveling in the two-phase medium according to a discrete step-by-step random walk mechanism. The probability that a carrier colliding with the interface will be reflected back into its phase of travel or cross into the other phase is determined on the basis of the conductivities of the two phases meeting at the interface. The computed values of effective conductivity are compared with variational bounds and analytical approximations of the literature.