Summary: We study the power-assignment problem in radio networks, where each radio station can transmit in one of two possible power levels, corresponding to two ranges – short and long. We show that this problem is NP-hard, and we present an \(O(n^{2})\)-time assignment algorithm such that the number of transmitters that are assigned long range by the algorithm is at most \((11/6)\) times the number of transmitters that are assigned long range by an optimal algorithm. We also present a \((9/5)\)-approximation algorithm for this problem whose running time is considerably higher.