Iron status was assessed by measuring serum ferritin and haemoglobin in a population survey in Copenhagen County, comprising 1359 nonpregnant women in age cohorts of 30, 40, 50, and 60 years; 809 were premenopausal and 550 postmenopausal. Premenopausal women had lower serum ferritin (median 37 micrograms/l) than postmenopausal women (median 71 micrograms/l), p < 0.0001. Of premenopausal women, 17.7% had ferritin < 15 micrograms/l (depleted iron stores), and 23.1% had ferritin levels of 15-30 micrograms/l (small iron stores). Corresponding figures in postmenopausal women were 3.3% and 10.3%. Iron deficiency anaemia (ferritin < 15 micrograms/l and haemoglobin < 121 g/l) was observed in 2.6% of pre- and 0.36% of postmenopausal women. After menstruations had ceased, there was a steep rise in ferritin levels, being most pronounced during the first 7 postmenopausal years. Pre- and postmenopausal multipara had lower ferritin than nulli- and unipara (p < 0.04), indicating that pregnancy and childbirth had a long lasting reducing influence on iron stores. The use of oral hormonal contraceptives had a marked increasing effect on iron stores, being correlated to the number of years the women had been taking the pill.