A randomised, controlled trial of 1429 women was carried out to compare 'active' management of the third stage of labour, using i.v. Ergometrine 0.5 mg, with a method of 'physiological' management, in women at 'low risk' to haemorrhage. In the "active" management group a higher incidence of the following complications was found:- manual removal of placenta (p less than 0.0005), problems such as nausea (p less than 0.0005), vomiting (p less than 0.0005), and severe after-birth pains (p less than 0.02), hypertension (p less than 0.0001) and secondary postpartum haemorrhage (p less than 0.02). The incidence of postpartum haemorrhage (blood loss greater than 500 ml) and postnatal haemoglobins less than 10 gm/100 were higher in the 'physiological' group (p less than 0.0005, p less than 0.002). No difference was found in the need for blood transfusion in either group. The routine use of i.v. Ergometrine 0.5 mg during the third stage of labour in women at 'low risk' to haemorrhage does not appear to be necessary and has many adverse effects. Further studies comparing different methods of 'physiological' management are recommended in order to reduce to a minimum the incidence of postpartum haemorrhage and anaemia.