Ever since the petroleum industry came into existence in Iran, healthcare services have been provided in this sector. After nationalization of the petroleum industry and establishment of National Iranian Oil Company (NIOC), healthcare services were provided by an NIOC Directorate.  

In 1998, an independent organization affiliated with NIOC was established under the title of Petroleum Industry Healthcare Services Organization, later renamed Petroleum Industry Health (PIHO).

PIHO is required by its Constitution to provide healthcare services to the employees (their families included) of the four affiliates of Ministry of Petroleum – NIOC, National Iranian Gas Company (NIGC), National Petrochemical Company (NPC) and National Iranian Refining and Distribution Company (NIORDC) – and their subsidiaries.

PIHO is currently providing services to 15 geographical areas: Ahvaz, Abadan, Aghajari, Gachsaran, Bushehr Province, Masjed Soleiman, Tehran, Isfahan, Markazi Province, Lorestan Province, northern provinces, northeastern and northwestern provinces, Fars Province, Hormuzgan Province, and Mahshahr.

PIHO provides services via 9 hospitals, 1 diclinic, 24 polyclinics, 69 family dispensaries, 89 occupational health centers and 71 medical assistance centers.