In 27 nursing mothers a study was made on breast milk fluoride (F) levels and the 24-h intake of F through foods and beverages. The daily F intake averaged 22.1 mg (range 9.5-37.2 mg); cooked food contributed 11.7 mg, water 4.5 mg and tea 5.8 mg. The breast milk F concentration averaged 0.033 mg/l (range 0.011-0.073 mg/l). No significant correlation could be established between the milk F level and the intake of F. The milk F level was, however, correlated positively to mothers' age and negatively to mothers' weight. It is concluded that the milk fluoride level was only moderately increased by the high intake of F, and that the children's intake of F through mothers' milk was negligible compared to the very high F intake through complementary foods and beverages.