Use of cod liver oil, which is rich in vitamins A and D, is traditionally recommended during the fall and winter months as a protective measure against vitamin D deficiency in several countries. It is not known whether childhood cod liver oil intake is related to variations in bone mineral density (BMD) or fractures in adult life. In 2001, a total of 3,052 Norway women aged 50-70 years had forearm BMD measured in a substudy of the population-based Nord-Trøndelag Health Study. Women reporting no childhood cod liver oil intake had statistically significantly higher BMD than those with any ingestion of cod liver oil. The odds ratio for low BMD (>1 standard deviation below age-specific mean) in women reporting cod liver oil intake throughout the year as compared with women with no intake was 2.3 (95% confidence interval: 1.4, 3.9), adjusted for body mass index, smoking, menopausal status, estrogen use, and current milk consumption. There were indications of a negative dose-response effect of childhood cod liver oil intake on bone. Although the vitamin A content of commercial cod liver oil was recently reduced by 75% in Norway, the past high concentration remains a possible explanation for the observed negative association between childhood cod liver oil intake and forearm BMD.