A multicentre, randomized, double-blind, placebo-controlled study was conducted to evaluate the efficacy and safety of ranitidine 150 mg and 300 mg in 342 patients with erosive oesophagitis. Treatment was given four times daily, and continued for 12 weeks or until healing (that is, normal or only erythematous mucosa). Erosive oesophagitis healing rates, as determined by endoscopy, were significantly greater in ranitidine-treated patients by 4 weeks compared with those of placebo-treated patients. By 12 weeks, erosive oesophagitis healing rates were 83 and 81% for ranitidine-treated patients (150 and 300 mg, respectively) and 58% for placebo-treated patients (P less than or equal to 0.001, ranitidine vs. placebo). Symptomatic relief was achieved within 24 hours after starting either dosage of ranitidine. Heartburn frequency (P less than 0.001) and severity (P less than 0.001), as well as antacid consumed per week (P less than 0.001), were reduced in both ranitidine groups in comparison with placebo. Healing rates and symptom relief were similar in the two ranitidine groups. Both dosages of ranitidine were well tolerated. Ranitidine (150 mg) given four times daily appears to be as effective as 300 mg ranitidine given four times daily in patients with moderate to severe oesophageal erosions.