Samples were collected from surface sea sediments at seven sites in the northern Adriatic Sea; there were six sites in proximity of industrial complexes and one from a tourist site (recreational beach). The samples were assayed for alkanes and polycyclic aromatic hydrocarbons. The composition of the hydrocarbon samples suggested that industrial pollution was present in most cases. A sample from one site was also grown aerobically under crude oil enrichment in order to evaluate the response of indigenous bacterial populations to crude oil exposure. Analysis of 16S rRNA gene sequences showed varying microbial biodiversity depending on the level of pollution - ranging from low (200 detected genera) to high biodiversity (1000+ genera), with lowest biodiversity observed in polluted samples. This showed a considerable biodiversity in all the sediment samples, which was severely restricted after selection on crude oil. Phylogenetic analysis of putative alkB genes showed a high evolutionary diversity of the enzymes in the samples and suggested considerable potential for bioremediation and bioprospecting. We present the first systematic analysis of bacterial communities from sediments of northern Adriatic sea that will provide a baseline assessment that may serve as a reference point for the eco - system changes and hydrocarbon degrading potential - a potential that could soon gain importance due to plans for oil exploitation in the area.