Background: Men with prostate cancer experience adjuvant androgen deprivation therapy (ADT) differently. Objective: To evaluate ADT effect on quality of life, the experience of clinical check-ups, and differences in cancer information as explanatory factors. Design, setting, and participants: All living men (400/695), randomized in the Scandinavian Prostate Cancer Group Study Number 4(SPCG-4) to radical prostatectomy (RP) or watchful waiting (WW) and a control group of 281 men were sent a study-specific questionnaire. Intervention: ADT Outcome measurements and statistical analysis: Self-assessed quality of life, worry at clinical check-ups, and amount of information received. Estimated relative risks with associated 95% confidence intervals (CI) for risk comparisons between groups using a log-binomial regression. Results and limitations: The SPCG-4 men had a median follow-up of 12.2 years, a median age of 77.0 years, 26% in the RP-group received ADT treatment and 40% in the WW-group. High quality of life for men without ADT was 36% for the RP-group, 44% for the WW- group and 45% for the control group. High quality of life for men with ADT was 30% for the RP-group and 20% for the WW-group. Men with ADT in the WW-group received significantly less information about the disease than men with ADT in the RP-group. Receiving no or little information about the prostate cancer disease was reported by 17% of men with ADT in RP-group and 39% among men with ADT in WW-group; relative risk 0.44 (95% CI 0.22-0.89). At clinical check-ups men treated with ADT had significantly higher levels of worry, regardless of study group than men without ADT. Limitation: lacking longitudinal data and a low number of ADT in RP- group. Conclusion: Men in WW without ADT reported levels of high quality of life comparable with men without prostate cancer. ADT treatment in the WW-group was associated with the lowest scores for all psychological parameters and they reported to be least informed about prostate cancer and its consequences. Patients summary: Good communication and information from caregivers is associated with less negative psychological effects at a disease progression.