In this paper, we address the issue of transmission power control in wireless ad-hoc networks. In general, it is assumed that minimum transmission power achieves the optimal throughput of the ad-hoc network because it produces minimum interference. However, this assumption can be realized under high node density which is not typical. Therefore, we show that using the minimal transmission range might not always results in optimal throughput performance. Using both throughput and throughput per unit energy as the optimization criteria, we demonstrate that the optimal transmission power is generically a function of the number of stations, the network grid area, and the traffic load. In particular, we show that the optimal power is a function of the network load for typical network scenarios. Finally, we propose two transmission power control algorithms called CPC, and IPC that adjust the transmission power adaptively, based on the network conditions to optimize throughput performance.