The super(210)Pb radioactive dating technique on two cores from the northern part of the Lagoon of Venice gives an average sedimentation rate of 0.7 cm/year. This is used to date the vertical profiles of member of DDT, Hg, Cd, Pb, Cr, Cu, Ni, Co, Zn and Fe concentrations. A maximum member of DDT concentration is found at a depth of 10 cm, corresponding to about 1955, in accordance with the time of the largest use of this pesticide in the area drained by the Dese river. Due to antropogenic origin the concentrations of heavy metals in the upper sediment layers are 1.3-12.7 times higher than those in the lower ones. The average concenttrations of these elements in the layers below 80 cm are tentatively proposed as natural background concentrations for the Lagoon of Venice.