Chronic interstitial nephritis with diffuse zonal fibrosis (CINF) occurs in Japanese Black cattle (Wagyu) as an autosomal recessive disorder leading to death prior to puberty, first six months or a year of life. We performed a genome-wide scan using microsatellite markers in a Wagyu pedigree segregating for CINF and mapped the CINF locus to bovine chromosome 1. CINF was closest to microsatellites BM9019 and INRA49 (Z score = 12.0; P < 3.4 x 10(-10)).