[en] A systematic study of human milk contamination due to the Chernobyl fall-out was conducted from May 1986 to December 1988 in the Rome area. A comparison was made with the contamination in the same period in other infant food, that is, cows' and powdered milk. The thyroid and effective dose equivalent for breast fed infants born in different periods were evaluated. Using average main food contamination data in the same area, an assessment of the transfer coefficient between the mothers' diet and their milk was performed. ⁴⁰K content of this milk was also measured and is discussed in the paper. An extension of the sampling to other areas was made in 1987 and 1988. (author)