  We investigate quantum teleportation through noisy quantum channels by
solving analytically and numerically a master equation in the Lindblad form. We
calculate the fidelity as a function of decoherence rates and angles of a state
to be teleported. It is found that the average fidelity and the range of states
to be accurately teleported depend on types of noise acting on quantum
channels. If the quantum channels is subject to isotropic noise, the average
fidelity decays to 1/2, which is smaller than the best possible value 2/3
obtained only by the classical communication. On the other hand, if the noisy
quantum channel is modeled by a single Lindblad operator, the average fidelity
is always greater than 2/3.
