IN THIS issue of the Archives, Levine and collaborators1 described the results of a trial using the histamine2 blocker nizatidine as a prophylactic agent against nonsteroidal antiinflammatory drug (NSAID)鈥攊nduced ulceration of the upper gastrointestinal tract. Four hundred ninetysix predominantly white female patients with osteoarthritis were enrolled in a multicenter, double-blind, placebocontrolled trial of nizatidine, 150 mg twice a day, vs placebo and followed up endoscopically on a monthly basis for 3 months. The end point of the study was development of an ulcer of either the stomach or the duodenum. Although neither ulcer occurrence nor symptoms were improved by therapy with nizatidine, the data indicated that, in a subgroup of patients with either a prior history of peptic ulcer disease or age greater than 65 years, ulceration occurred less frequently in those taking nizatidine. However, neither duodenal nor gastric ulcers, when evaluated independently, showed an effect by treatment