OBJECTIVES: Androgen deprivation therapy (ADT) can be delivered either surgically by orchiectomy or medically via luteinizing hormone-releasing hormone (LHRH) drugs. They are considered therapeutically equivalent in the treatment of advanced prostate cancer (PCa) but use of orchiectomy has drastically decreased since the approval of LHRH drugs in the 1990s. The objective is to describe the use of orchiectomy for PCa and analyze factors associated with orchiectomy treatment over medical castration in the province of Quebec. METHODS: The cohort consists of men diagnosed with PCa from 2004-2012 and treated by ADT (either by LHRH drugs or by orchiectomy), extracted from a random sample from Quebec public healthcare insurance databases. Multivariable logistic regression analysis was performed to identify variables associated with orchiectomy treatment. RESULTS: We identified 7096 patients treated by ADT, of which 106 (1.5%) underwent orchiectomy. The median age at ADT initiation was 75 years. Following multivariable analyses, age over 80 (odds ratio [OR] 1.60, 95% confidence interval (CI), 1.06-2.43, p = 0.018) and higher Charlson comorbidity score (OR 1.09, 95%CI 1.01-1.17, p = 0.024) were associated with increased odds of orchiectomy. Conversely, patients treated with a local radical treatment prior or within 3 months after ADT initiation (OR 0.18, 95%CI 0.07-0.46, p < 0.001), residing in a region with university-affiliated hospitals (OR 0.39, 95%CI 0.26-0.58, p < 0.001) were associated with lower odds of orchiectomy treatment. Also, year of ADT initiation was associated with lower odds of orchiectomy (OR 0.88 for each increasing year from 2004-2014, 95%CI 0.81-0.95, p = 0.002). CONCLUSIONS: A minority of PCa patients are treated by orchiectomy. These men were likely to be older, more comorbid, not treated by local radical treatment, living in a region not serviced by a university-affiliated hospital, and initiated ADT in earlier years compared to patients treated by medical castration.