This study identifies marine bacteria obtained from three sites along Comodoro Rivadavia coast, south of Argentina. Seawater and intertidal sediment samples were collected. Two of the sites were located close to the city sewage system (CR1, CR2) and the third one (CR3) was near from an oil buoy. Bacterial counts were performed on four culture media: BBR, BRN, mineral medium with crude oil and gas oil and ENDO for coliforms. The identification of bacteria was performed by using fatty acid methyl esters. The counts resulted positive to total coliforms and faecal coliforms in sites CR1 and CR2 and resulted negative in site CR3 except in autumn. We isolated 469 strains, to which a fatty acid extraction and identification were performed. The system identified 37 genera and 54 species in only 236 strains. The other strains were unidentified because they were not found in Sherlock data base. Pseudoalteromonas was the genus frequently found isolated and the enterobacteria group was conformed by Citrobacter, Enterobacter and Escherichia. The principal components analysis related the winter season to Gram positive strain, and autumn season was asociated to the biggest biodiversity of genera.