The Tehran Metro () is a rapid transit system serving Tehran, the capital of Iran. It is the largest metro system in the Middle East. It is also one of the busiest metros in the Middle East. The system is owned and operated by Tehran Urban and Suburban Railway. It consists of 6 operational metro lines (and an additional commuter rail line), with construction under way on three lines including west extension of line 4, line 6 and north and east extension line 7.