Patients with prostate cancer often have lower urinary tract symptoms and are often prescribed hormone therapy. Although it is prescribed with the aim of controlling the cancer, favourable effects on these symptoms have also been reported in many studies. Our aim was to conduct the world’s first systematic review of this literature. Articles were included if they quantitatively assessed the effect of hormone therapy on the urinary symptoms of patients with prostate cancer using a standardised scale. Fourteen articles describing 5365 patients were included. The most commonly used test was the International Prostate Symptom Score (IPSS). The median initial IPSS score was 14.3, suggesting moderately severe symptoms. The median improvement in that score was 29%, or approximately 4 points, indicating a clinically significant improvement. For those patients with a higher initial IPSS score, greater improvements were seen. Improvements in other tests, including the urological quality of life score, urodynamics, post-voiding residual volumes and reductions in prostate gland volume, were often also reported. We offer a panel of suggestions for future research.