Background. Advanced prostate cancer patients treated with androgen deprivation therapy (ADT) have been shown to experience a large number of physiological and psychological sequelae; however, few studies have examined how these sequelae affect the patients' and their partners' quality of life (QOL). Purpose. The purposes of this study were: (1) to describe and compare patients' and partners' levels of self-efficacy, symptom distress. communication, appraisal, coping and QOL and (2) to determine if specific antecedent factors (self-efficacy, symptom distress, communication, their partners' QOL), and mediators (appraisal of illness/caregiving, active and avoidant coping) explain a significant amount of variance in the QOL of advanced prostate cancer patients treated with ADT and their partners. Theoretical framework. The study was guided by a stress-coping model. Methods. The study was a cross-sectional. secondary analysis of data obtained from two randomized clinical trials. The study sample consisted of 75 patient-partner dyads. Data were obtained using standardized measures with acceptable reliabilities. Independent t tests were used to assess differences between patients and partners scores on major study variables. Bootstrapping was used to assess for mediator effects and structural equation modeling was used to assess the the models function to predict QOL. Results. Patients and partners were more alike than different. Partners reported worse emotional QOL than patients. Patients and partners had poorer emotional QOL when compared to an age and gender matched normative sample. Appraisal (illness/caregiving) and avoidant coping were significant mediators between antecedents variables and QOL for both patients and partners. Partners' QOL was a significant predictor of patients' QOL. Patients' QOL was not a significant predictor of partners' QOL. Overall, the stress-coping model accounted for a significant amount of variance in patients' and partners' QOL (89% and 74%. respectively). Conclusions. Findings suggest that advanced prostate cancer patients treated with ADT and their partners are at risk for poorer emotional QOL. Results also indicate that there are a number of potential areas for interventions to improve patients' and partners emotional QOL: self-efficacy, symptom distress, communication, appraisal and avoidant coping.