Offshore structures are installed to produce hydrocarbons, but at some point in time during the life cycle of the field, when the cost to operate a structure exceeds the income from production, the structure will exist as a liability instead of an asset. Federal regulations require that an offshore oil and gas lease be cleared of all structures within one year after production on the lease ceases. In recent years, the Minerals Management Service has begun to encourage operators to remove structures on producing leases that are no longer "economically viable." The purpose of this paper is to quantify the amount of idle iron that exists in the Gulf of Mexico and to describe its geographic distribution and ownership patterns. The basic question of what idle iron is and why it exists is addressed, followed by a discussion of the policy implications involved in the interpretation of federal regulations. Summary statistics that quantify and define the idle iron inventory is then presented.