A prototype least cost pipeline routing was performed using various data and GIS analysis. Ahvaz-Marun oil pipeline in south west of IRAN was chosen for development of the prototype. The Ahvaz-Marun pipeline was about 34-km and carries Ethan gas from Marun Petrochemical Company (MPC) to Ahvaz. A model was developed incorporating pipeline length, topography, geology, land use, stream, wetland, road and a railroad crossings to identify a least cost pathway. Geospatial Information System (GIS) analysis was used for spatial modeling and overlay. Costs associated with terrain conditions, geology and landuse were given from actual costs that are used in the section of pipeline design of Iranian National Petroleum. The length and cost associated with existing pipeline that made by traditional approaches were compared those of the least cost pathway through GIS best path analysis. The existing pipeline path is 34-km long, and the least cost pathway is 35- km long. Although longer in length, t...