It is assessed that heartburn with associated oesophagitis is experienced by 45% to 70% of pregnant women. Posture is the most constant associated factor; bile regurgitation through the pylorus is likely to be important in its aetiology but gastric acidity is not. Treatment with alkalis or dilute hydrochloric acid affords some relief in 95% of cases and patient acceptability is the most important factor in choice of preparation. Hiatus hernia is likely to be present in severe cases and rupture of the oseophagus has been reported. Early delivery may be advisable in the interest of the mother.