Polychlorinated biphenyl compounds (PCBs) were analyzed in sediments and clams' soft tissues from sampling sites in the Mekong River delta from the border with Cambodia to the coast of South China Sea. Concentrations of 13 individual PCB congeners are reported. Median concentration of SigmaPCB congeners was 0.279 ng g(-1) dry weight (range 0.106-2.016 ng g(-1) dry weight) in sediments, and 5.20 ng g(-1) dry weight (range 1.89-19.37 ng g(-1)) in clams. Distribution and bioaccumulation of PCBs in the delta are discussed. It is concluded that in the Mekong River delta PCB concentrations were generally lower than in other regions of Vietnam and their likely sources have been waste discharges from repair workshops and other facilities in the delta cities.