To study the effect of calcium and vitamin D supplementation on the incidence of toxaemia of pregnancy, 200 randomly selected pregnant women (supplemented group), were put on calcium (375 mg/day) and vitamin D (1,200 IU/day) supplements at 20-24 weeks of pregnancy onwards. Another 200 pregnant women constituted the non-supplemented group. At 32 and 36 weeks of pregnancy the systolic and diastolic blood pressure of non-toxemic women was significantly lower in the supplemented group than in the non-supplemented group. However, the incidence of toxaemia in the supplemented group (6%) was not significantly different from that in the non-supplemented group (9%).