A combination of hypoparathyroidism, sensorineural deafness, and renal dysplasia has been considered to be a new syndrome inherited in an autosomal dominant fashion; we name the condition "HDR syndrome." We describe a Japanese girl who has HDR syndrome associated with de novo del(10)(p13). The chromosome deletion suggests that the putative gene(s) responsible for HDR syndrome is located at a 10pter-->p13 region.