The levels of p,p'-DDT, p,p'-DDE, dieldrin, alpha- and beta-hexachlorocyclohexane (alpha-HCH, beta-HCH), hexachlorobenzene and polychlorinated biphenyls (PCBs) were determined in milk fat from mothers with different dietary habits. The categories studied comprised mothers eating a lacto-vegetarian diet (18 milk samples), a mixed diet (20 milk samples) and a mixed diet which regularly included fatty fish from the Baltic (11 milk samples). The lowest levels of p,p'-DDT+p,p'-DDE and PCBs were found in milk from lacto-vegetarians and the highest levels in milk from mothers who regularly consumed fatty fish from the Baltic. Factors other than the diets which could influence the levels of the organochlorine compounds are discussed, e.g. mother's age, amount of milk produced and mother's weight loss.