DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) is one of the pesticides that are hazardous for the environment and human health. Effective environmental-friendly treatment using co-cultures of fungi and bacteria is needed. In this study, the bacteria Bacillus subtilis at various volumes of 1, 3, 5, 7, and 10 mL (1 mL approximate to 6.7 x 10(8) CFU) were mixed into 10 mL of the brown-rot fungus Fomitopsis pinicola culture for degrading DDT during a 7-days incubation period. DDT was degraded by approximately 42% by F. pinicola during the 7-days incubation period. The addition of 10 mL of B. subtilis into F. pinicola culture showed the highest DDT degradation of approximately 86% during the 7-days incubation period. DDD (1,1-dichloro-2,2-bis(4-chlorophenyl)ethane), DDE (1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene), and DDMU (1-chloro-2,2-bis(4-chlorophenyl)ethylene) were detected as metabolic products from DDT degradation by co-cultures of F. pinicola and B. subtilis. Transformation pathway was proposed in which DDT was transformed into three pathways as follows: (1) dechlorination to DDD, (2) dehydrochlorination to DDE, and (3) formation of DDMU.