Bacteria are diverse and abundant in soils, but only a few bacteria have known to grow on hydrocarbon-contaminated areas and utilize complex carbon source such as crude oil for the synthesis of polyhydroxyalkanoate (bioremediation potential and the ability to produce important biopolymers). Among 32 samples collected from several sites of petroleum refinery soil and oily sludge of Iranian southwestern refineries, 45 oil-degrading pseudomonads were identified, and 33 % of the isolated Pseudomonas strains were able to produce polyhydroxyalkanoate using Gachsaran crude oil (2 % v/v) as carbon source. The repeated monomer composition of the copolymer produced from Gachsaran crude oil was determined by gas chromatography/mass spectrometry. The produced monomers composites contained: C8 (3-hydroxyoctanoate), C10 (3-hydroxydecanoate), C12 (2-hydroxydodecanoate), C14 (3-hydroxytetradecanoate), and C16 (3-hydroxydecahexanoate), which are known as biopolymers. This study indicates oil-contaminated areas can be important sources for polyhydroxyalkanoate producers which can be used for the bioremediation of crude-oil-polluted sites; also polyhydroxyalkanoate has a functional role in bacterial survival and stress tolerance in the toxic environments and poor nutrient availability.