A gain control circuit for an optical amplifier includes a feed-forward path which enables the pump power of an excitation laser to be controlled based on input power of the amplifier. The feed-forward path is complemented by a feed-back loop which includes: a subtractor that outputs an error signal based on a difference between scaled input power and output power of the optical amplifier; a regulator which generates a bias and correction signal that reduces the error signal to zero; and an adder which adds the bias and correction signal to the input power signal of the feed-forward path. The output of the adder forms a pump control signal which maintains a desired gain of the amplifier irrespective of fluctuations in input power and channel load changes, as well as other influences. Through the use of purely electronic control, the control circuit controls the gain of the amplifier with substantially less pump power than conventional circuits utilizing other known methods. Further, the feed-forward path eliminates gain sag which degrades the performance of many conventional amplifier circuits. Preferably, the control circuit is dynamically adapted to the non-linear dynamic behavior of the optical amplifier. This will advantageously result in a substantial improvement in speed of the amplifier control.