Menetrier's disease is a rare condition characterized by marked proliferation of gastric mucosa with variable mucus secretion and achlorhydria. Although crude mucus secretion and gastric aspirates have been evaluated in this disease for output of dry matter, hexosamine, fucose, protein content, and transforming growth factor alpha activity, we report for the first time the isolation, purification, and gel electrophoresis of mucin from crude mucus scrapings. The fragmentation pattern of mucin in Menetrier's disease demonstrated less large polymeric mucin than the control. There was also a band of approximately 55-65 kd M, on polyacrylamide gel electrophoresis similar to that found in gastric carcinoma or peptic ulcer, but absent in the control specimens.