Folate and iron nutrition was studied in a total of 122 pregnant, lactaging, and non-pregant, non-lactating Korean women, Serum folate levels were determined microbiologically using Lactobacillus casei(ATCC 7469), and serum iron levels was analyzed colormetrically. The average folate values of pregnant and lactating women were 5.42ng/ml and 4.14ng/ml, which were significantly lower than that of the non-pregnant, non-lactating women(7.06ng/ml). More than 1/3 of the total subjects were found to have serum folate levels lower than 3ng/ml, at which folate nutrition status can be considered inadequate. Serum iron values of pregnant(96.9ug/dl)and lactating women(93.9ug/dl) were not significantly different from that of the non-pregnant, non-lactating women (97.1ug/dl). There were however, more iron-deficient subjects in the pregnant gorup(17%) and the lactating group(19%) than in the non-pregnant, non-lactating group (8%). A statistically significant positive correlation was shown between the levels of serum folate and iron in lactating women(r=.9694, p<0.05). The results of our study document that folate deficiency is a nutritional problem as prevalent as iron deficiency in Korean women, especially during pregnancy and lactation. For these women a routine folate and iron supplementation might be necessary.