In chronic illnesses, such as prostate cancer, multiple health outcomes need to be considered. This project focused on two types of health outcomes: health-related quality of life (HRQoL) and cognitive function. The first aim was to investigate cognitive effects of pharmacological androgen-suppressing treatment. Numerous studies have shown cognitive performance to be associated with sex hormones. One of the main groups of drugs used for hormonal ablation in men with prostate cancer, the luteinising hormone releasing hormone (LHRH) agonists, has been associated with adverse cognitive effects in controlled studies in women and in case reports of female and male patients. However, there have been no published studies on the effect of LHRH agonists and other androgen-suppressing treatments on cognitive functioning in male patients. The second aim was to investigate the effect of treatments on HRQoL in men with prostate cancer. There are few randomised treatment studies of HRQoL in these patients. The third aim was to study additional predictors of HRQoL, examining stress and coping theory as a theoretical basis for understanding individual differences in HRQoL. The fourth aim was to examine patients' subjective experiences of prostate cancer. To investigate these questions, 82 men with non-localised prostate cancer were randomly assigned to receive leuprorelin (LHRH agonist), goserelin (LHRH agonist), cyproterone (steroidal antiandrogen), or close clinical monitoring. These patients and 20 community volunteers matched for age, marital status, and general health undertook medical, psychosocial, and cognitive assessments before treatment and after 6 and 12 months of treatment. The main question for statistical analysis was whether dependent variables would show Group x Time interactions in the predicted directions. Compared with baseline assessments, men administered androgen suppression monotherapy performed worse in 3/12 tests of attention, memory, and executive function. Twenty-six percent of men randomised to active treatment demonstrated clinically significant decline in one or more cognitive tests at 6 months compared with baseline performance. By contrast, no community volunteers or patients randomised to close monitoring showed decline in test performance. Men on hormonal treatments reported impaired sexual function on treatment compared with baseline assessments. Men assigned to close monitoring and cyproterone treatment reported increased emotional distress over time. Groups did not differ in change in existential satisfaction, subjective cognitive function, physical symptoms, or social and role functioning. For individuals, hormonal treatments were more frequently associated with decreased physical, sexual, social and role functioning, but were also associated with improved HRQoL for some individuals. In hierarchical regression analysis, HRQoL was lower for men who had more comorbid illnesses, a history of neurological dysfunction, higher threat appraisals, or higher use of emotion-focused coping strategies. Coping strategies also showed some longitudinal associations with HRQoL, even when earlier levels of HRQoL had been taken into account. Subjective reports demonstrated that many patients viewed prostate cancer as a relatively manageable problem. Several patients said that other health problems affected them more than prostate cancer, whereas no patient said that prostate cancer was worse than other problems. Comments about the seriousness of prostate cancer were equally divided between patients who reported it as very serious (14.3% of patients) and those who saw it as a relatively minor problem (14.3%). Other patient observations were grouped into categories of personal responses to prostate cancer, health, and health research; life circumstances that were not directly associated with health; attributions about medication; and function prior to the study. The results demonstrated that pharmacological androgen suppression therapy was associated with impaired memory, attention, and executive function in male patients. Hormonal treatments and close monitoring had differential effects on patients' HRQoL, particularly in terms of sexual function and emotional distress. HRQoL was also associated with appraisal and coping, to a greater extent than it was associated with medical variables, supporting the applicability of stress and coping theory for these patients. Observations from participants placed these findings in the context of participants' concerns, demonstrating that issues such as cognitive and sexual function were relevant for these patients. These findings suggest that cognitive function should be given increased attention as a health outcome, not only in "neurological" disorders but also in other "non-neurological" conditions such as prostate cancer. They also support continued efforts to understand both beneficial and adverse effects of treatments for chronic illness on HRQoL and individual factors that affect health outcomes.