Biological methods for remediation of soils is based on the degradation of pollutants due to activity of microorganisms (bacteria, fungi). Effectiveness of biological decontamination of soils depends on the following factors: biodegradation of pollutants, type of microorganisms used, choice of oxidant and nutrient and subject to clean up environmental characteristics. Ex situ techniques for bioremediation of soils polluted are: composting (static / mechanical agitation), land farming and biopiles. Techniques in situ bioremediation of soils polluted are: bioventingul, biospargingul and biostimulation – bioaugumentarea.