Background: The addition of docetaxel to standard androgen deprivation therapy (ADT) has been shown to improve the survival of men with metastatic hormone-sensitive prostate cancer (MHSPC) (Sweeney 2015, James 2016). We noticed PSA progression in some of our patients (pts) during docetaxel treatment and reviewed their outcomes. Methods: Men with MHSPC treated with docetaxel were identified from an electronic oncology pharmacy database. Eligible pts were prescribed docetaxel for metastatic adenocarcinoma of the prostate within 120 days of initiation of ADT. Pts with castration-resistant disease (CRPC), other histologies, and those without metastatic disease were excluded. Demographic, clinical, treatment and outcome data were extracted retrospectively from electronic medical records. Results: 31 eligible pts with MHSPC treated with docetaxel between August 2014 and July 2016 were identified. Median age was 65 years (53-83) and 28 (90%) had high-volume disease as defined by Sweeney et al (2015). Nadir PSA levels 6-7 months from ADT initiation were < 0.2, 0.2-4, and > 4 ng/mL in 29.0%, 36.7% and 36.7%, respectively. At median follow up of 85 weeks, 45.2% of pts had progressed to CRPC and 22.6% had died. Median time to CRPC was 59 weeks and median overall survival was 85 weeks. Seven pts with high-volume disease (25%) had PSA progression while receiving docetaxel treatment. The median overall survival of this group was 26 weeks (17 to 106+) and six have died. Three had visceral metastases. Nadir PSA was < 0.2 (1 pt), 0.2-4 (2 pts) and > 4 ng/mL (4 pts). After docetaxel 2 pts received BSC alone and 5 pts had 1^st-line CRPC therapy. No response to abiraterone/enzalutamide was seen (3 pts). Two pts who discontinued docetaxel immediately at PSA progression and were switched to alternative chemotherapy survived > 1 year. Conclusions: A subset of men with MHSPC has lethal docetaxel-resistant disease characterized by early PSA rise. It is important to recognize these patients, but it is not clear if standard CRPC therapies are effective. An immediate early switch to alternative chemotherapy may be helpful. Further research to predict early docetaxel resistance, characterize response to current therapies and identify more effective treatment is needed.