The market power problem in Iranian electricity market is addressed in this study. This paper by using various structural indices of market power and reviewing market results analyzes the intensity of competition in Iran's electricity market and examines whether this market is functioning at an appropriate level of efficiency. In this article the most well-known indices of market power are calculated in two approaches for two different scenarios (current situation and future outlook of generation sector's ownership in Iran's power industry). Comparing the results of these scenarios promises more competitive market for the second scenario. Calculating Residual Supply Index for Iran's power market shows despite admissible values of concentration ratios, due to supply scarcity during periods when the demand is close to the total available capacity, some suppliers can exercise market power even with a relatively small market share. The most important price and load indices like weighted average prices and load/price duration curves of Iranian electricity market during March 2007-March 2008 are also analyzed in this paper. These results imply the existence of economic withholding. The main limiting factors of competition and significant implemented countermeasures for market power mitigation in Iran's electricity market are also mentioned. (C) 2010 Elsevier Ltd. All rights reserved.