One hundred and twenty-one women with history of a previous child with atopic disease were randomly allocated during the next pregnancy to antigen avoidance or control groups. Dietary advice consisted of almost complete exclusion of milk and dairy products, egg, fish, beef and peanut throughout pregnancy and lactation. A total of 109 completed the study. Maternal antigen avoidance was associated with reduced occurrence of atopic eczema and the skin involvement was less extensive and milder. The beneficial effect was observed mainly in the breast-fed group. Among the fifty-five who completed the trial of antigen avoidance, seventeen infants developed atopic eczema, five out of thirty-five who were breast-fed and twelve out of twenty who were formula-fed. Among the offspring of fifty-four control mothers given no dietary restriction, eczema was observed in twenty-four infants, eleven out of thirty-six breast-fed and thirteen of eighteen formula-fed. Avoidance of common dietary allergens during pregnancy and lactation enhanced the preventive beneficial effect of exclusive breast feeding on the incidence of atopic eczema among infants at high risk.