A nationwide Swedish case-control study of 388 men and 63 women with adenocarcinoma of the oesophagus and gastro-oesophageal function and 676 men controls and 140 women investigated whether sex differences in aetiology contribute to male predominance. Compared with men, women seemed more vulnerable to reflux (odds ratio (OR)=4.6, 95% confidence interval (CI)=2.0-10.5 vs OR=3.4, 95% CI=2.5-4.6), obesity (OR=10.3, 95% CI=2.6-42.3 vs OR=5.4, 95% CI=2.6-10.8) and smoking (OR=5.3, 95% CI=2.0-14.1 vs OR=2.8, 95% CI=1.9-4.2), less harmed by low intake of fruit and vegetables (OR=0.9, 95% CI 0.3-2.4 vs OR=1.6, 95% CI=1.1-2.2) and less protected by Helicobacter pylori infection (OR=0.5, 95% CI=0.3-0.8 vs OR=1.6, 95% CI=0.5-5.4).