Microbial degradation of resins and asphaltenes by indigenous soil microflora has been studied under laboratory conditions on model soil systems. It has been shown that high-molecular-mass heteroatomic components of oil are available for the oxidation by soil microorganisms; within 180 days of the experiment the utilization of resins and asphaltenes was 41.5 and 35.0 wt %, respectively. Analysis of the residual products of biodegradation showed a marked change in the composition of high-molecular-mass heteroatomic components. Biodegradation of resins and asphaltenes occurs predominantly with the "detachment" of peripheral paraffin structures, the aromatic ring is converted substantially less.