In this paper, we present a new coded cooperation strategy which benefits from the combination of space-time codes and opportunistic relaying (OR) method. In this strategy, the relay is selected in an opportunistic manner and then cooperates with the source using distributed space-time code. Our analysis indicates that this new strategy is outage-optimal. It equals in outage behavior to the coded cooperation that employs all potential relays. The advantage of this strategy is that it saves considerable amount of coordination overhead among relay nodes and it also reliefs the difficulties of designing effective spacetime codes. We analyze and derive the outage probability of DF relaying for BPSK transmission. Numerical results are given to verify our analysis.