IgA nephropathy is the most common kidney disease diagnosed in biopsy samples from patients with inflammatory bowel disease (IBD), according to new findings. In a retrospective case series of kidney biopsy samples from 83 patients with IBD, 24% of patients were diagnosed with IgA nephropathy, 19% with interstitial nephritis, 12% with arterionephrosclerosis, 8% with acute tubular injury, 7% with proliferative glomerulonephritis and 5% with minimal-change disease. Moreover, the diagnostic prevalence of IgA nephropathy was higher in the IBD kidney biopsy samples than in 33,630 non-IBD kidney biopsy samples obtained during the same time period (24% versus 8%, P <0.001).