In a randomized controlled trial 201 healthy nulliparous women were randomly allocated by means of a computer generated randomization list. From 20 weeks of gestation until delivery they received either 2 g of oral elemental calcium (n = 103) per day or an identical placebo (n = 98). Eleven women (5.47%) were lost to follow-up after randomization. The study groups were very similar at the time of randomization; with respect to several clinical and demographic variables. Treatment compliance was very similar in both groups as was determined by pill count.1 The rate of pregnancy induced hypertension was lower in the calcium group than in the placebo group 8.24%; vs 29.03%; (RR = 0.28; 95% CI 0.14–0.59). The incidence of gestational hypertension was 6.18% in the calcium group and 17.20% in the placebo group (RR = 0.28; 95% CI 0.08–0.80), and the incidence of preeclampsia was 2.06% in the calcium group and 11.82% in the placebo group (RR = 0.13; 95% CI 0.01–0.64). In conclusion calcium supplementation given in pregnancy to nulliparous women reduces the incidence of pregnancy induced hypertension.