The levels of petroleum hydrocarbons in the tissues and shells of Melanopsis nodosa from Tigris River within the City of Baghdad were investigated. Forty eight samples of snails and sediments collected once every two months for the period November 2014 to May 2015 from two stations (AL-Kadhimiya and AL-Qadisiyah) along Tigris River were analyzed by using Gas Chromatography. The levels of total petroleum hydrocarbons ranged from 0.22 µg/g to 3.48 µg/g in tissues, from 0.10 µg/g to 2.65 µg/g in shells, and from 0.14 µg/g to 2.58 µg/g in sediments. Results of statistical analysis showed significant differences in total petroleum hydrocarbon levels between study stations. The levels at AL-Kadhimiya station were significantly higher than at AL-Qadisiyah station.