Background IgA nephropathy is the major cause of end-stage renal failure in patients with primary glomerular diseases. Tumor suppressor cylindromatosis (CYLD), the recently identified member of the deubiquitinating enzymes, has been actively involved in regulation of inflammation. This study was undertaken to investigate the CYLD expression profile in IgA nephropathy and identify factors associated with CYLD expression. Methods Forty-one cases of IgA nephropathy were selected. CYLD expression in the kidney biopsy tissue was measured by immunohistochemical staining. Relevant clinical and pathological data were analyzed, and Logistic regression analysis was carried out to identify factors associated with CYLD expression. Results CYLD was specifically expressed in renal tubular epithelial cells in 70% of the studied patients with IgA nephropathy. All patients with positive CYLD staining had proteinuria, while only 72.7% of patients with negative CYLD had proteinuria (P=0.003). Among studied proteinuric patients, those with positive CYLD had significantly less tubulo-interstitial lesions and higher estimated glomerular filtration rate (eGFR) levels when compared with those patients showed negative CYLD results. Logistic regression analysis indicated that the urinary protein excretion and eGFR were identified as predictors for the CYLD expression. Conclusion CYLD is expressed in renal tubular epithelial cells and appears to be associated negatively with tubulointerstitial lesions, however, its exact functional role remains to be clarified in further experiments. Chin Med J 2009;122(21):2603-2607