Increasing population, standard of living, and industrial development has all resulted in production of considerable amounts of solid wastes. More than 3.5 million tons of waste is produced throughout the world daily, out of which I.R. Iran’s share is about 40,000 tons/d. Like other developing countries in the region, relatively large percentages of organic waste and high moisture contents are the main characteristics of the municipal solid waste (MSW) in Iran. High moisture content of the waste plus that portion of the precipitations, which percolates through landfilled waste material results in the formation of large amounts of leachate. Most of the landfills in Iran do not have any engineering leachate collection system. The only leachate collection strategy, which is practiced in landfills of large cities include the setting of the base slope in a way to direct the leachate to a large holding pond. The most common practice for management of the collected leachate at present time is to benefit from the evaporation potential which would cause many environmental and sanitation problems such as odder, air pollution and also distribution of diseases by some animals. Leachate recirculation is one method of leachate management, which at the same time could enhance biodegradation and stabilization of waste material in landfills. In this research performance of aerobic, anaerobic and semi-aerobic bioreactor landfills was investigated at laboratory scale. Three reactors, with a 0.5 by 0.5 m cross section and 1.0 m height were filled with MSW with a density of 550 kg/m 3 . Two containers were used to store and recirculate leachate for each bioreactor cell. An air compressor was user for injection of air into aerobic cell. Air injection was 0.24 lit/min.kg at the beginning and was reduced over time. Aerobic cell was maintained and monitored for 75 days while the anaerobic and semi-aerobic cells were maintained and monitored for 157 days. COD removal efficiencies for aerobic, semi-aerobic and anaerobic bioreactor cells were 91, 93 and 92 percent respectively. Results of this study showed that bioreactor landfills are capable of reducing heavy metal content of leachate. Semi-aerobic and anaerobic bioreactor cells performed better than aerobic bioreactor cell in term of heavy metal removal. Collection and analysis of gases form anaerobic bioreactor cell contained about 58 percent methane.