The biodegradation of DRO compounds was evaluated by the processes of natural attenuation and bioaugmentation in mangrove soil. Prior to the experiments, a consortium of bacteria capable of degrading hydrocarbons was isolated and identified: Pseudomonas aeruginosa, P. luteola, Sphingomonas paucimobilis and P. fluorescens. For natural attenuation, mangrove oil contaminated soil was placed in horizontal tubular reactors with air supply and no addition of bacteria. While for bioaugmentation three initial inocula from bacterial consortium (0.02, 0.04 and 0.06 g L^-1 biomass dry weight) were added to the mangrove soil, maintaining aeration and moisture (30%). The samples were collected every 30 days during 3 months and the oil content was analyzed with a gas chromatograph (GC). The degradation of diesel oil range (40.3%) was higher with an inocula size of 0.06 g L^-1, where C₁₂, C₁₈ and C₂₆ were the most susceptible to degradation, while in the process of natural attenuation only 4.51% was removed, suggesting that the low nutrient content in the mangrove soil and bacteria number could limit the hydrocarbon degradation. Therefore it is possible to increase the degradation through bioaugmentation in a system as the mangrove soil.