Prostate cancer is detected today at earlier stages and in younger men than ever before. A lot of men are asymptomatic and also physically and sexually active at diagnosis, and most of them are being treated by curative procedures. These trends have led to increasing numbers of patients undergoing disease management for longer periods of time. For many patients quality of life (QoL) may be just as important as survival. Thus, QoL considerations may well be the critical factor in medical decision-making for most of them. Widespread interest in studying patient-centred outcomes has led to the development of methods for health-related QoL measurements. In fact, many questionnaires have been introduced in clinical practice to assess the impact of QoL in patients (SF-36, CARES, FACT, EORTC QLQ-C30, GRISS, UCLA PCI, PCOS). Herein we evaluate the impact of QoL on patients affected by prostate cancer and treated with watchful waiting, radical prostatectomy, radiotherapy and hormonal therapy; we have also considered the role of supportive care, including the administration of analgesics, antidepressants, corticosteroids, bisphosphonates, antiemetics and stool softeners, together with psychological support. The ultimate goal of QoL research should strongly improve medical care and concretely assist patients and physicians in treatment decision-making.