Purpose: It is important to meet the supportive care needs of cancer patients to ensure their satisfaction with their care. A population-wide sample of men younger than 70 years and newly diagnosed with prostate cancer was surveyed to determine their unmet needs in five domains and the factors predicting them. Patients and Methods: Eligible men were younger than 70 years and residents in New South Wales, Australia, with newly diagnosed histopathologically confirmed prostate cancer. Sixty-seven percent of eligible men diagnosed between October 2000 and October 2001 participated. Demographic, treatment, and self-reported health data were collected. Information on cancer stage, grade, and prostate-specific antigen was obtained from medical records. Logistic regression analyses determined patient and treatment variables that predicted higher unmet needs. Results: More than half (54%) of men with prostate cancer expressed some level of unmet psychological need, and 47% expressed unmet sexuality needs. Nearly one fourth expressed a moderate or high level of unmet need with respect to changes in sexuality. Sexuality needs were independently predicted by being younger, having had a secondary school education only, having had surgery, and being married, living as married, or divorced. Uncertainty about the future was also an important area of unmet need. Conclusion: Attention should be given to sexual and psychological needs in the early months after diagnosis or treatment of prostate cancer, particularly in younger men, those with less education, and those having surgery. Research into better ways of meeting these needs will enable us to meet them with as much rigor as we meet clinical treatment needs.