A 10Gbit/s limiting amplifier IC for optical transmission system was implemented with AlGaAs HBT technology. Amplifier was designed to support differential input and output. Small signal performance of the packaged IC achieves 26dB gain and f(3dB) of 8GHz. A single output has 800mV(p-p) swing with more than 26dB dynamic range. The performance of the limiting amplifier was verified through single mode fiber 320km transmission link test.