An extensive survey was carried out to aid in understanding the role of indigenous microorganisms in the removal of oil from Northwestern Atlantic temperate to arctic marine environments. The presence of hydrocarbon-utilizing microorganisms was demonstrated in sediments and adjacent waters taken from Bermuda, Canadian Northwest Atlantic and Eastern Canadian Arctic marine shorelines. In addition, surface-water samples (5 m depth) taken at 11 different stations along a transect between Halifax and Bermuda, with one exception, showed the presence of significant numbers of hydrocarbon-utilizing microorganisms. The hydrocarbon-utilizing bacteria present included Nocardia, Pseudomonas, Flavobacter, Vibrio, and Achromobacter species. The fraction of the total heterotrophic bacteria represented by the hydrocarbon utilizers ranged up to 100% depending upon the area's previous history of oil spillage; the bulk of the values were less than 10%. The frequency of specific hydrocarbon utilization in decreasing order was hexadecene-1, pristane, hexadecane, dibenzothiophene, anthracene, and decalin. The location, numbers, variety, and broad capacity of the microbial hydrocarbon utilizers illustrate their ubiquity and indicate the microbial potential for removal or conversion of oil in the environments examined.