Objective To compare the efficacy and side effects of misoprostol, compared with methylergometrine, Design A double-blind, randomised clinical trial of 200 women with apparently normal pregnancies.Setting University teaching hospital.Participants Two hundred women with apparently normal pregnancies.Methods After the baby had been born, all women received two capsules by mouth and the contents of an ampule by intravenous injection. Each woman only received one active product. The capsules contained either a total of 600 pg misoprostol or placebo, and the ampule 200 pg of methylergometrine or placebo.Main outcome measures Need for further oxytocic drugs, blood pressure, the presence of side effects, mean haemoglobin and haematocrit three days after delivery.Results Two hundred women completed the study (100 received methylergometrine and 100 misoprostol). Postpartum haemorrhage occurred in 4.3% of the methylergometrine group and 8.3% of the misoprostol group ( P = 0.57). The need for further oxytocic drugs was 4.4% and 12.8% after methylergometrine and misoprostol, respectively (P = 0.065). One hour after the birth of the baby there was no difference in the mean systolic blood pressure (117 k 12 mmHg versus 115 f 11 mmHg) ( P = 0.26) or the mean diastolic blood pressure (72 k 10 mmHg versus 7 1 k 11 mmHg for the groups receiving methylergometrine or misoprostol, respectively) (P = 0.97). The mean temperature in the misoprostol group rose to 37.4"C, compared with 37°C in the methylergometrine group (P c 0.0001). In the misoprostol group 34% developed fever (> 38°C) compared with 3% in the methylergometrine group ( P < O~OOOl). Shivering (visual analogue score 2 8) also occurred more often after misoprostol (42%) than after methylergometrine (8.5%) (P c 0.0001). The haemoglobin level (g/dL) on the third postpartum day was similar for both groups (1 1 . O and 11.2 for methylergometrine and misoprostol, respectively) (P = 0.39).Conclusions This study suggests that although protection from postpartum haemorrhage using parenteral methylergometrine and oral misoprostol is nearly equal, misoprostol is associated with more side effects.for the prevention of postpartum haemorrhage.