Tissue norepinephrine (NE) content and quantitative morphometric analysis of benign prostatic hyperplasia (BPH) were evaluated in 30 patients with symptomatic BPH. BPH specimens were obtained by transurethral resection, and NE content was evaluated by high-performance liquid chromatography. The proportions of smooth muscle fibrous, and glandular elements were determined by the light microscopic stereological method. Norepinephrine content of the prostate correlated well with the proportion of smooth muscle component (r = 0.749, P < 0.0001). The percentage of fibrous tissue element was positively correlated with prostate size (r = 0.459, P = 0.0099). Norepinephrine content and histological components did not correlate with subjective symptom score. Morphometrical findings and NE content did not correlate with uroflowmetry parameters and postvoid residual urine rate. In conclusion, NE content of the prostate was probably determined by the amount of smooth muscle element in BPH tissue. The fibrous tissue element was increased in large hyperplastic tissue. The severity of BPH could not be explained by differences in histological composition alone.