To reduce the frequency of the need for hospital visits for patients with prostate cancer (PCa) taking androgen-deprivation therapy during the SARS-CoV-2 (COVID-19) pandemic, we switched them from gonadotropin-releasing hormone (GnRH) antagonist to a long-acting luteinizing hormone-releasing hormone (LH-RH) agonist. Here, we confirmed the efficacy and safety profile of this switching. We analyzed the medical records of 32 patients with PCa who received ADT and switched from GnRH antagonist to a long-acting LH-RH agonist during the COVID-19 pandemic, evaluating hematological and serological variables, including serum testosterone and prostate-specific antigen. Before and after the switching from GnRH antagonist to LH-RH agonist, the median serum testosterone levels were 0.22 and 0.18 ng/ml, respectively, and the median serum prostate-specific antigen levels were 0.18 and 0.11 ng/ml, respectively. No changes in the rates of flare-ups of conditions or adverse events were observed. Switching from GnRH antagonist to a long-acting LH-RH agonist appears to be a reasonable option that does not diminish efficacy or exacerbate adverse events.