Microbial treatment of bis(2-ethylhexyl)phthalate (BEHP) contaminated soil was evaluated in batch and sequencing batch reactors (SBR) using a mixed bacterial culture isolated from a BEHP-contaminated site. The BEHP-degrading mixed culture had three predominant component strains, Brevibacterium iodinum, Rhodococcus luteus and Bacillus brevis. For soil slurry SBR studies, the hydraulic residence times (the quotient of the reactor volume by the volumetric flow rate, theta (H)), ranging from 3 to 30 days were evaluated. The degradation rates in the SBR system were much higher than in a standard batch reactor probably due to higher microbial activity, as evidenced by microbial counts and oxygen uptake rates. The volumetric removal rates for SBRS ranged from 0.23 to 2.31 g/l per day for different residence times. The inter-relationships between residence time, biomass, oxygen uptake rates and BEHP removal were determined.