Background: The decision to provide adjuvant therapy to men with high risk pathology after radical prostatectomy (RP) is confounded by tremendous uncertainty. We prospectively evaluated the impact of a previously validated genomic classifier (the Decipher test, henceforth referred to as GC) which predicts metastasis risk after RP, on urologists’ decision-making for adjuvant treatment. Methods: 150 adjuvant patients were enrolled into the study by 43 urologists; 19 community and academic practices. Patients with pathologic T3 staging (pT3) or positive surgical margin (SM+) after RP were included. Physicians provided a management recommendation prior to obtaining GC and again upon receiving results. Patients completed validated surveys on decision quality and PCa-related anxiety. Results: Results were available for 141 patients. Median patient age at RP was 64 years; 66% and 51% had pT3 and SM+ pathology, respectively. The median 5-year predicted probability of metastasis by GC was 5.0% (interquartile range [IQR] 2.2%-10.7%). GC classified 48%, 20% and 32% of men as low-, intermediate- and high-risk, respectively. Pre-GC, observation was recommended for 88%; 12% received a recommendation for adjuvant radiation therapy (ART). Post-GC, 18% (95% CI 12-26%) of treatment recommendations changed, including 9% of low-risk and 31% of high-risk patients. Decisional Conflict Scale (DCS) scores decreased (indicating higher decision quality) after exposure to GC results (median DCS pre-GC 25 [IQR 10-44], median DCS post-GC 20 [IQR ], p < 0.001). GC results were associated with the decision to pursue ART in multivariable logistic regression (OR 1.47; 95% CI 1.18-1.83). Conclusions: Observation is the predominantly prescribed management strategy among PCa patients with high risk features at RP. Knowledge of GC results was associated with treatment decision-making among these patients: patients at low risk for metastasis had higher rates of observation recommendations and patients at high risk had higher rates of ART recommendations. Decision quality was improved for patients exposed to GC results. Clinical trial information: NCT02080689