Nutritional anaemia, thought to be caused by iron deficiency, affects 50-70% of pregnant women in the developing world. The influence of vitamin A and iron supplementation was studied in anaemic pregnant women in West Java, in a randomised, double-masked, placebo-controlled field trial. 251 women aged 17-35 years, parity 0-4, gestation 16-24 weeks, and haemoglobin between 80 and 109 g/L were randomly allocated to four groups: vitamin A (2.4 mg retinol) and placebo iron tablets; iron (60 mg elemental iron) and placebo vitamin A; vitamin A and iron; or both placebos, all daily for 8 weeks. Maximum haemoglobin was achieved with both vitamin A and iron supplementation (12.78 g/L, 95% Cl 10.86 to 14.70), with one-third of the response attributable to vitamin A (3.68 g/L, 2.03 to 5.33) and two-thirds to iron (7.71 g/L, 5.97 to 9.45). After supplementation, the proportion of women who became non-anaemic was 35% in the vitamin-A-supplemented group, 68% in the iron-supplemented group, 97% in the group supplemented with both, and 16% in the placebo group. Improvement in vitamin A status may contribute to the control of anaemic pregnant women.