We studied the iron status of 400 Italian subjects, 200 men and 200 women, equally distributed in four 10-year age groups between 20 and 60 years. The frequency of iron deficiency was elevated in women of childbearing age. On average 13% of the women in the three younger age groups showed low serum ferritin levels and 16-18% a low transferrin saturation index. Only 6% of the women over 50 were iron deficient. Signs of iron deficiency were never observed in more than 2% of the men in the age groups under 50, with the percentage rising slightly in the men over 50. In the women an inverse correlation was found between serum ferritin levels and number of births [log ferritin (ng/ml) vs number of births, b +/- SE (b): -0.252 +/- 0.088] and between serum ferritin and duration of menstruation [log ferritin (ng/ml) vs duration of menstruation (days), b +/- SE (b): -0.160 +/- 0.065]. Furthermore, hemoglobin levels were 0.700 (+/- 0.248, SE) g/dl lower in the women with 'abundant menstrual flow', and hemoglobin levels correlated inversely with number of births [hemoglobin (g/dl) vs number of births, b +/- SE (b): -0.354 +/- 0.115]. Our study showed an elevated frequency of iron deficiency in women of reproductive age. The number of births and abundance of menstrual flow were both important factors in predisposing younger women to developing iron deficiency.