A 40-Gb/s optical clock recovery is demonstrated using an injection-locked optoelectronic oscillator (OEO). Injection locking is achieved by directly coupling a return-to-zero optical data stream to a photodiode in the OEO. This scheme is advantageous in its simple configuration, wavelength-independent operation, and wide locking range. The pulsewidth and root-mean-square jitter of the recovered clock are 9.8 ps and 283 fs (10 Hz-18.6 MHz), respectively. Furthermore, subharmonic clock recovery from a 160-Gb/s optical time-division-multiplexed data stream is achieved using the same configuration.