This is, to my knowledge, the second reported case of diffuse familial polyposis of the colon with electrolyte depletion syndrome. Efforts to reverse this severe depletion with vigorous oral and intravenous therapy were unsuccessful, but colectomy halted the loss and produced a reversal of the patient's clinical course. Several interesting aspects of both conditions are discussed. It appears that the histologic villous pattern is the significant factor in fluid and electrolyte loss, since I found no reported cases with the more usual adenomatous configuration to produce this syndrome.