Omeprazole 60 mg once daily was compared with ranitidine 150 mg twice daily in an endoscopically-controlled, double-blind randomised trial in 51 outpatients with erosive or ulcerative reflux oesophagitis (grade 2 or 3). Endoscopy was repeated after 4 weeks and, in the absence of healing, again after 8 weeks. Symptoms were assessed before entry and after 2, 4, and 8 weeks. Patients who were unhealed after 8 weeks were blindly switched to the other drug and treatment was continued for another 4 to 8 weeks. The healing rate (change to grade 0 or 1 oesophagitis) after 4 weeks was 19 of 25 patients treated with omeprazole and 7 of 26 patients treated with ranitidine (p = 0.002). The corresponding figures after 8 weeks were 22 of 25 and 10 of 26 (p = 0.001). The higher healing rate with omeprazole was reflected in a significantly faster and stronger improvement of reflux symptoms. 13 patients, who were unhealed after 8 weeks on ranitidine, were healed after switching treatment. Healing was achieved in 1 of 3 patients who were switched to ranitidine. There were no adverse events or changes in laboratory variables of clinical importance. Omeprazole is superior to ranitidine in the short-term treatment of reflux oesophagitis.