Hydrocarbon-utilizing bacteria have been found widely distributed in natural environments, their proportions affected by many factors, such as level of previous hydrocarbon exposure and from variations in soil conditions. This research compares microbial enumeration, diversity, and respiration between contaminated and adjacent uncontaminated soils and three native agricultural soils from Manitoba at a variety of depths. The purpose is to understand the effects of hydrocarbon contamination on these microbial parameters and the usefulness of the parameters for implementing intrinsic remediation as a remedial option. Four contaminated soils were examined, varying in the type of previous hydrocarbon exposure (two diesel fuel, one coal tar, and one crude oil). The enumeration of aliphatic and aromatic degrading microorganisms from contaminated versus adjacent uncontaminated soils and agricultural soils were examined using a most-probable number method. The effect of previous contamination on the microbial diversity of soils was examined in a second experiment. The final experiment was to determine differences in degradation rates in contaminated versus uncontaminated soils and agricultural soils upon the addition of 14C-labelled phenanthrene. (Abstract shortened by UMI.)