In November 1991, toxigenic Vibrio cholerae O1 infection was confirmed in two unrelated persons in Hawaii. Cholera had not been acquired in Hawaii since 1895. To determine the source and extent of V cholerae O1 infections in Hawaii, both patients were interviewed, suspect food sources were investigated, and surveillance of physicians, laboratories, hospitals, and sewage treatment plants was instituted. One patient's husband had serologic titers consistent with recent V cholerae O1 infection; no other cases were confirmed and V cholerae O1 was not recovered from active surveillance of laboratories or sewage treatment plants. The investigation demonstrated that the outbreak had affected few persons and had ended.