To reduce interference and fading effect, the use of power control is the most eligible way. We consider power control in a cooperative communication system consisting of multiple sources and multiple relays and the relay is assumed to be amplify-and-forward. We proposes a new distributed power control algorithm for cooperative relaying(DPCCR). In this distributed algorithm, each source updates its power level iteratively using estimates of the inverse of the signal-to-interference and noise ratio(SINR) of its own channel. We analyzes convergence properties of proposed algorithms by using standard techniques. Simulation results show that a respectable decrease in system outage performance and power saving can be achieved, when compared with other power control algorithm without relaying.