Biofiltration was performed for 50 days in a perlite-packed biofilter (8 cm I.D.×105 cm height) for the simultaneous removal of toluene and dimethyl sulfide (DMS). Two strains, Rhodococcus pyridinovorans PYJ-1 and Gordonia sihwaniensis PKL-1, were cocultured in the biofilter. Removal efficiencies of toluene and DMS at an empty bed residence time (EBRT) of 3min were 80-85% and 40-45%, respectively, for an input concentration of 2.5-3.0 mg/L of toluene and 1.5-2.0 mg/L of DMS. The pH of the perlite column was maintained at 7.0-7.2, and the moisture content varied from 61% at the bottom to 51% at the top. Starting from the same initial cell concentration (2.4×106 CFU/g of wet packing) the number of R. pyridinovorans PYJ-1 was 2.5 times higher compared with that of G. sihwaniensis PKL-1 after 50 days of operation.