Purpose: The Grade Group (GG) classification is recommended by guidelines as a reliable prognostic factor of prostate cancer. However, most studies have been performed on the Caucasian population. Our objective was to validate GG classification as a safe way to classify intermediate- and high-risk patients with African ancestry. Patients and methods: This was a retrospective study in an Afro-Caribbean population. A total of 1236 patients were included between 2000 and 2015. Patients were stratified according to (GG). Survival analysis was performed using the Kaplan–Meier method, univariate and multivariate analyses using the Cox model. Results: There was no significant difference at 5 and 10-year BCR-free survival between the intermediate- and high-risk groups, based on the D'Amico classification. There was a highly significant difference in BCR-free survival at 5 (p < 0.0001) and 10 years (p < 0.0001) for patients of GG 1 and 2 vs 3, 4, and 5, respectively. There was no significant difference in 5-year BCR-free survival of patients of GG grades 1 and 2, whether lymph-node dissection was performed or not. There was a significant difference between GG 2 and 3 patients in 5 (p = 0.008) and 10-year BCR-free survival (p = 0.01). High PSA (p < 0.0001), pathological GG ≥ 3 (p < 0.0001), pathological stage pT3 (p < 0.0001) and positive margins (p < 0.0001) were factors for BCR in multivariate analysis. Conclusion: The GG 2015 classification appears to be a better prognostic factor than D'Amico classification for intermediate- and high-risk Afro-Caribbean patients. [ABSTRACT FROM AUTHOR]