OBJECTIVES: To establish whether routine evaluation of light microscopic changes in bladder biopsies in men with graded bladder outlet obstruction correlates with urodynamic parameters and to evaluate the performance of two pathologists in bladder biopsy interpretation. METHODS: In 63 consecutive patients presenting with lower urinary tract symptoms suggestive of bladder outlet obstruction, the workup included bladder biopsies, which were semiquantitatively and independently evaluated by two pathologists for fibrosis, elastosis, muscle cell degeneration, inflammation, and additional remarkable findings. Furthermore, as determined by their general impression, the pathologists gave a diagnosis of normal or graded abnormality. The pathologists' performance was compared and the clinical and urodynamic data were correlated to the consensus histologic diagnoses. RESULTS: Fifty-four of 63 cases could be evaluated. The intraobserver and interobserver reproducibility were reasonable, with a kappa of 0.35 and 0.50, respectively. The consensus diagnosis of abnormal bladder biopsy correlated with impaired bladder compliance and capacity. However, no correlation was found between the presence and severity of histologic abnormalities and Schafer class, urethral resistance factor, instability, postvoid residual urine volume, symptom score, and prostate volume. CONCLUSIONS: Although abnormal bladder biopsies correlated significantly with impaired bladder capacity and compliance, routine evaluation of bladder biopsies is not indicated in the evaluation of bladder outlet obstruction.