Introduction. Prostate cancer is the most common type of cancer found in American men. Patient adjustment to prostate cancer is not limited to attempts to restore sexual function, a process that can pose significant challenges to couples following most surgical and nonsurgical treatments. Patients often struggle with depression and other relational stressors. Partners also undergo psychosocial, relational, sexual, and quality-of-life changes and their responses to these changes may relate to patient adjustment. Aim. To evaluate to what extent partners' psychosocial and relational adjustment relates to prostate cancer patient adjustment. Main Outcome Measures. Partner and patient general and sexual depression; patient relationship satisfaction, quality of sexual communication, sexual satisfaction, and life satisfaction. Method. A total of 77 patients and 57 partners responded to a mail survey that included demographic information, the Beck Depression Inventory, Life Satisfaction Index, Index of Sexual Satisfaction, Relationship Assessment Scale, Dyadic Sexual Communication Scale, Sexuality Scale, and Client Satisfaction Questionnaire. Results. Patients and their partners differed in their sexual self-esteem, sexual depression, sexual preoccupation, and life satisfaction. Both had greater levels of depression, poorer quality of sexual communication, and more sexual dissatisfaction than the general population. Partners' level of general depression and depression concerning their sex lives were significant predictors of patients' relationship satisfaction, perceived quality of communication about the sexual relationship, and sexual satisfaction after controlling for patients' general and sexual depression. Conclusion. Partners often serve as primary caregivers, thus partner adjustment can be critical to the health of the patient and to his primary relationship. Results suggest the importance of including partners' adjustment in assessing patient adjustment post-treatment. We suggest that physicians working with these patients partner with mental health professionals who can help couples address the challenges they encounter and extend the continuity of care when the need for medical intervention has passed.