Hereditary angioedema (HAE) is known as a deficiency state of C1 inhibitor (C1 INH), an important protease inhibitor protein involved in the complement system. As with other components of the classical pathway of the complement system, a state of its deficiency often causes clinical immunoregulatory disorders. A 45-yr-old brother and a 63-yr-old sister with HAE both developed chronic renal failure, probably due to chronic glomerulonephritis, and required regular hemodialysis. This is, to our knowledge, the first report of sibling cases of HAE associated with chronic renal failure.