Semiconductor laser diodes may play an important role in synchronous optical networks as sources of optical modelocked pulse trains with robust timing stability. In this paper, it is demonstrated how injection modelocked semiconductor lasers can be used in all-optical clock recovery systems. Experimental measurement of clock recovery dynamics shows that these devices offer robust clock recovery with low injected data power (less than 6 uW), large repetition rate locking bandwidth (2.9 X 10-3 fractional bandwidth), and small timing jitter (less than 93 fs). Clocking from an injected data stream at 1/50th the clocking repetition rate is demonstrated.