Environmental monitoring is a tool used to assess the current issues and to take actions. Global warming and oil spills add adverse effects to sustainability of the environment safety. There are many causes that contribute to pollution in oil-related environment: tanker accidents and poor maintenance practices, natural spills, off-shore activities and land-based oil activities. Oil is of crucial importance to the national economy of Oman. Oil Refining and crude oil exporting take place in Mina Al Fahal which is the main oil exporting zone to the world in Oman. Previous studies for the assessment of oil pollution had been done mainly in Mina Al Fahal. A gas chromatograph equipped with mass spectrometer (GC/MS) was used in this study for hydrocarbon analysis. The petroleum hydrocarbons in the collected intertidal sediments were in the range of 16.8 (+ 0.93) to 6394.5 (+ 206) ug/kg dry- wt. The highest value (6394.5 = 206 ug/kg-dry wt.) was obtained in the collected sediments where the liquid effluent was flowing close to it on its way to the sea. Traces of petroleum hydrocarbons (16.8 +0.93-19.0+ 1.15 ug/kg-dry wt) were found opposite to Oman Refinery Company (ORC). In the area where the terminal operations of crude oil take place, the concentration of petroleum hydrocarbons was in the range of 19.5 (+ 0.91) to 27.6 (+3.47) ug/kg dry-wt. The petroleum hydrocarbons in the collected subtidal sediments were in the range of 20 (+ 0.60) to 1693 (+ 385) ug/kg dry-wt. Petroleum hydrocarbons were not detected in the area opposite to Oman Refinery Company. In the zone of the terminal operations of crude oil, hydrocarbons with a range of 831 (+216) to 1693 (+ 385) ug/kg dry-wt was obtained. The levels of petroleum hydrocarbons were below the detection limit (6.15 ug/l) in the collected seawater samples. Concentrations of the discharged liquid effluents, collected at different distances of the channel, were in the range of 85.2 (+ 36.6) to 241.6 (+ 9.1) ug/1. The acceptable level of disposing effluent to the Omani marine environment is 15 mg/L (MECA, 2005).