The combination of a histamine H2-receptor antagonist and a muscarinic receptor antagonist has been reported to result in greater suppression of intragastric acidity than either agent alone. The present randomized, double-blind, multicentre trial compared the effects of the oral combination of 150 mg ranitidine b.d. plus 50 mg pirenzepine b.d. with 150 mg ranitidine b.d. plus placebo pirenzepine b.d. in the treatment of patients with reflux oesophagitis. All 157 patients had symptoms of gastro-oesophageal reflux with endoscopically confirmed oesophageal erosions (Savary and Miller grades I-III). After four weeks of treatment, healing rates were 32/75 (43%) in the combined treatment group and 34/76 (45%) in the group receiving ranitidine alone. After eight weeks, the cumulative healing rates had increased to 48/72 (67%) and 51/75 (68%), respectively. More patients receiving ranitidine plus pirenzepine had complete relief of day- and night-time heartburn after four weeks compared with those receiving ranitidine alone (day: 59% vs. 38%, P = 0.02; night: 69% vs. 52%, P = 0.04). After eight weeks, symptom relief was comparable in both groups. Clinical adverse effects were reported by nine patients receiving ranitidine and by 19 patients receiving the combination. It is concluded that combining ranitidine with pirenzepine does not aid the healing of reflux oesophagitis but does improve symptom relief at four weeks.