The Monte Carlo method is applied to the problem of radiant heat transfer to a nonisothermal absorbing and emitting gray gas between gray walls. The solutions are compared to limiting cases of black walls and large optical thickness available in the literature. The Monte Carlo procedure was found to be simply and quickly formulated for complex cases which cannot be readily attacked by standard analytical techniques. The numerical results were quickly obtained with the use of a high speed electronic computer. This method also gives greater physical insight into the behavior of the system.