In this letter, we propose and analyze an amplify-and-forward (AF) relaying system for coherent free-space optics (FSOs) applications. In particular, we derive, in series expressions, the lower bound of the outage probability of the proposed system using modal compensation to mitigate the atmospheric turbulence-induced amplitude fluctuation and phase aberration. The performance of the derived lower bound of the outage probability is confirmed by the very tight Monte-Carlo simulation result. We show that the coherent FSO AF relaying system could be used for practical applications in case of Zernike compensation mode J = 20, requiring the SNR of 32.5 dB in the outage probability of 10(-6). It is also noted that the AF relaying system is comparable in performance with the DF relaying system.