Surface sediments (10 cm) of the subtropical Shatt Al-Arab estuary and Northwest Arabian Gulf were collected to study the fatty acids distribution and sources .Samples were analyzed by gas chromatography. Other relevant parameters were measured including total organic carbon, and grain size. A total of 31 fatty acids were identified from the superficial sediment samples, including polyunsaturated PUFA, monounsaturated (MUFA), and saturated and branched fatty acids. The total FA (TFA ) concentrations were in the range 13.32-35.72 µg/g dry weight (dw).Generally, the abundances of the 31 FAs showing strong even/odd numbered predominance, and ranging from C12 to C32 were C14 (1.68-12.45%), C16 (2.92-13.49%), C18 (0.87-12.75), C19 (0.87-3.29%), C24 (0.19-6.99%) and C26 (nd-8.90%), C28(nd-5.91%). These distributions are indicative of input of terrestrial, phytoplanktonic and bacterial lipid residues. The sums of long chain FAs (LCFAs) C24-C32 concentrations of were calculated. High values of terrestrial Organic Matter (OM)were found at Shatt Al-Arab, the values were in the range 4.05-4.46 µg/g (dw), with contribution relative to the TFAs ranging from 12.49-21.99% (mean 17.99%). While low values were found at the North West Arabian Gulf , the values were in the range 0.03-0.09 µg/g (dw), with contribution relative to the TFAs ranging from 0.19-0.68 % (mean 0.36%).