OBJECTIVES To examine the prostates from patients with haematuria associated with benign prostatic hyperplasia (BPH) to determine their microvascular anatomy and thus assess histopathological differences in patients with significant haematuria. PATIENTS AND METHODS Prospectively, 11 patients with BPH and haematuria (mean age 70 years) and 19 control patients with BPH alone (mean age 72 years) were identified. Neither group had received hormone manipulation or had been catheterized. The sub-urothelial compartment of the prostatic urethra in subsequent specimens from transurethral resection was examined using factor VIII/CD-34 immuno-histochemistry. The microvessel density (MVD) was calculated by counting vascular cross-sectional profiles within a 0.81-mm2 grid. The pathologist studying the specimens was unaware of the patients' symptoms. RESULTS The median (range) MVD in the haematuria group was 64 (28-137) and in the controls was 27 (14-39) (P < 0.001). CONCLUSION The MVD was significantly greater in the patients with haematuria, suggesting that suburothelial microvessel proliferation may play an important role in mediating haematuria associated with BPH. This is the first time that a difference has been shown at the cellular level in patients with haematuria and could form an important foundation for subsequent research.