The aim of this study was to verify and to compare in benign prostatic hyperplasia (BPH) patients, the effect of finasteride versus dutasteride therapy on chromogranin A (CgA) serum levels, as a marker of neuroendocrine (NE) differentiation. Patients and Methods: This was a prospective randomised study in which 60 consecutive men with clinical diagnosis of BPH were randomised to a 6-month period of finasteride 5 mg/day versus dutasteride 4 mg/day versus control (no therapy). Total prostate-specific antigen (PSA), testosterone and CgA were analysed at randomisation and thereafter at one, three- and six-month intervals. Results: In both Group A (finasteride) and Group B (dutasteride), but not in Group C (no therapy), a statistically significant increase (p0.05) difference between Group A and B was found. Conclusion: In this population, 5-alpha reductase inhibitors, with no difference between finasteride and dutasteride, produced a significant increase in serum CgA levels, probably related to NE activation