Bull terrier hereditary nephritis is caused by a mutation that leads to an inadequate synthesis of collagen type IV, which is an important component in the basement membranes. The inheritance of the mutation is autosomal dominant in bull terriers and progression to renal failure takes variable time, from several months to ten years. Proteinuria is the first clinical sign of the disease and the diagnosis is confirmed by transmission electron microscopy of renal tissue where typical ultrastructural changes in the glomerular basement membrane (GBM), thickening and multilaminar splitting are found. This study was performed in order to find out the occurrence of hereditary nephritis in bull terriers in Sweden through examination of urine samples and renal tissue and comparisons with how the disease is described in the literature. Urine samples from 76 Swedish bull terriers were collected and examined for proteinuria.