The concentrations of Cu, Zn, Cd, Pb, Se, Hg, DDT, DDD, DDE, the PCBs and the chlordane components have been determined in the muscle, liver, kidney and blubber of the grey seal, Halichoerus grypus and the Baltic ringed seal Phoca hispida botnica of different ages caught in the Gulf of Finland. The results are related to the age and, for the organochlorine compounds, to the lipid content, of the specimens. Se and Hg were found to be correlated strongly with age. The heavy metal concentrations were highest in the liver, except for Cd, which was highest in the kidney. The mean concentrations of PCB and DDT compounds in blubber were varied and those for yearling seals were considerably lower thun those for older seals, but, even so, the levels were high from the biological point of view. Some comparisons with the results of earlier studies on seals in the Gulf of Finland and the Bothnian Bay are made and a short account of research into the seal uterus in relation to the high levels of PCB is given.