Five samples of cod-liver oil of Baltic origin, collected between 1971 and 1989, have been analysed for 15 selected polychlorinated biphenyl (PCB) congeners including the ten most toxic non-, mono-and di-ortho coplanar, IUPAC nos. 60, 77, 105, 118, 126, 138, 169 and 170 and another five highly bioaccumulative members (IUPAC nos. 28 + 32, 52, 101, 153 and 180). The method of measurement was capillary GC-MS. Cod-liver oils collected in 1971, 1975, 1980, 1985 and 1989 contained 3.0, 2.5, 6.7, 2.9 and 3.1 micrograms g-1 respectively, of selected PCBs (IUPAC nos. 28 + 32, 52, 101, 138, 153 and 180). The concentration of total PCBs in these oils were 8.0, 6.7, 17, 8.0 and 9.5 micrograms g-1, respectively for the years 1971-89, which indicates both persistency and steady state of these pollutants in the Baltic Sea. These cod-liver oils also showed high concentrations of the ten most toxic coplanar PCBs; their TEQ-values (Safe, 1990) were between 900 and 2300 micrograms g-1. 2,3', 4,4',5-pentachlorobiphenyl (IUPAC no. 118), 2,3,3', 4,4'-pentachlorobiphenyl (IUPAC no. 105) and 3,3',4,4',5-pentachlorobiphenyl (IUPAC no. 126) contributed most to the total TEQs of the ten coplanar members, occupying 47, 19 and 17%, respectively (totally 83%). A possible intake of these toxic PCBs from cod-liver oil by children or adults was estimated to be between 4.5 and 35 pg TEQ daily and for total PCBs between 34 and 260 micrograms daily.(ABSTRACT TRUNCATED AT 250 WORDS)