Background: Phase III clinical trials have demonstrated efficacy with an overall survival (OS) benefit for the addition of docetaxel (DOC) to androgen deprivation therapy (ADT) for the treatment of metastatic castration-sensitive prostate cancer (mCSPC). The clinical effectiveness of DOC with ADT in the general patient population remains undefined. Methods: A population-based retrospective review was conducted of patients (pts) with mCSPC who received DOC at the BC Cancer Agency from 04/2015 to 02/2017. Patient and disease characteristics were extracted. Safety and clinical-effectiveness were evaluated. Results: 183 records were identified; 156 pts received DOC in the mCSPC setting. Baseline characteristics included a median age of 67 years (range 44-86) and visceral metastases (mets) present in 18%; 80% had high volume disease with 74% having > 3, and 54% > 10 bone mets; 76% had de-novo metastatic disease. All 6 planned DOC cycles were delivered in 126 cases (81%); it was stopped early for: toxicity in 15 (10%), unrelated death in 1 (0.6%), pt preference in 5 (3%) or disease progression in 9 (6%) cases. Dose reductions and delays were required in 61 (39%) and 25 (16%) cases, respectively. Grade 3-5 adverse events were noted in 62 (40%) cases, with 28 (18%) cases of febrile neutropenia (FN); there were no treatment-related deaths. Pts with FN had more bone mets (p = 0.046), but there was no difference in time from start of ADT to initiation of docetaxel, age, baseline performance status, PSA, or visceral involvement. PSA ≤ 0.2 ng/L was achieved in 41 (28%) cases after 6 months of ADT and maintained in 13 (8%) cases after 12 months. 41% of pts had developed CRPC within 1-yr, with a median time to CRPC of 14.3 months. Treatment for CRPC was given in 54 cases, with most pts receiving either abiraterone or enzalutamide (87%) with a PSA decline ≥50% occurring in 47%. Conclusions: Effectiveness of DOC with ADT in a general population of pts with mCSPC was associated with poorer outcomes and high rates of toxicity compared to the phase III studies. Response rates to first-line treatment for mCRPC with abiraterone or enzalutamide appear similar to those previously reported.