We report a new X-linked recessive nephrolithiasis kindred. X-linked recessive nephrolithiasis is a recently described disease characterized by recurrent nephrolithiasis, nephrocalcinosis, and progressive renal failure, associated with mutations in a renal chloride channel gene, chloride channel number 5. Screening individuals at risk with renal ultrasonography and measurement of urinary excretion of low molecular weight proteins and calcium will exclude boys without X-linked recessive nephrolithiasis kindred and identify boys likely to have the disease.