The North Refineries Company is one of the 16 companies affiliated with the Iraqi Ministry of Oil. Its headquarters are located in Tikrit. It was established in 1976 under Law No. 101. At that time, the company was managed by the General Organization for Oil and Gas Refining. In 1997, Public Sector Companies Law No. 22 was issued, and the company's name became the North Refineries Company/Public Company.

The Middle Refineries Company is one of the 16 companies affiliated with the Iraqi Ministry of Oil. Its headquarters are in Baghdad and it was established in 1953.

The South Refineries Company is one of the 16 companies affiliated with the Iraqi Ministry of Oil. Its headquarters are located in Basra and it was established in 1969. It was built in 1969, and its facilities began production in 1974. The refinery is located 20 km west of Basra and has a capacity of 210,000 barrels per day.

North Gas Company is an Iraqi state-owned company responsible for gas production in northern Iraq. The company is located in Kirkuk.

The Iraqi Oil Tanker Company (IOTC) is an Iraqi state-owned company specializing in the maritime transportation of crude oil and refined products, established in 1972.

The company was established pursuant to Law No. (22) of 1997 on June 1, 1998, whereby the status of the public pipeline facility was adapted in accordance with the aforementioned law. The company's headquarters are in Baghdad/Dora. The company transports all types of petroleum products within Iraq from production sources to distribution and consumption outlets via a network of pipelines. These include pipelines transporting crude oil feeding refineries and some power plants, pipelines transporting dry and liquid gas through pipeline networks from production sources to consumption sites, and pipelines transporting white petroleum products (gasoline, kerosene, gas oil) and black petroleum products (fuel oil and crude oil). It also extends, rehabilitates, and maintains oil pipelines for our company and other companies, and maintains and operates pumping and receiving stations in oil depots throughout Iraq.

Heavy Engineering Equipments State Company " HEESCo" was established in 1963
Before more than half century to be one of the largest state industrial companies in Iraq specialized at manufacturing and erecting heavy engineering equipments required for many industrial fields with its highly qualified staff of about 1864 employees working at various fields ( engineering ,technical ,administrative ,..etc.).
During the last 50 years of its age HEESCO has been developing techniques and capabilities required to the production process throughout using highly advanced machinery from internationally well-known resources so that it can cope with the global technical standards needed for covering the local markets of gas/oil industries in particular .

In early stages, an experiment of marketing a small shipment of Iraqi crude oil received by Iraq's government which was produced by the International Oil Companies (IOCs) working in Iraq at that time, was the spark that led to the initiation of oil marketing in Iraq. The contract was concluded on  swap basis for medicines with a Greek company, since it was not possible to sell the shipment at the announced Official Selling Price (OSP) that was paid to the Iraqi government by the(IOCs) when the latter was conducting marketing of Iraqi crude oil back then.
Thereafter, a Marketing Department was established within the Economic Division of the National Oil Company (NOC) to assume responsibility for contracting and issuance of documents from Tripoli Port in Lebanon, aiming to provide training for the Iraqi staff in preparation for marketing direct investment oil on April 1972 from Al-FAO sea port that was rehabilitated for that purpose.

- Oil and gas production from oil and gas fields within the company's geographic area.
- Isolating and compressing associated gas and dome gases and transporting them to the North Gas Complex to produce liquid gas and dry gas for use as fuel for industrial purposes.
- Processing oil in concentration complexes and transporting it to refineries and export terminals.
- Providing drilling and well repair supplies in contracts with the Iraqi Drilling Company and foreign contractors, and implementing all supporting operations.
- Geological and reservoir control and studies, and field measurements.
- Research and quality control of crude oil, gas, and products.
- Implementing routine and scheduled maintenance work for the oil facility.