The next treatment strategy after drug holidays following docetaxel (DTX) therapy for patients with castration-resistant prostate cancer (CRPC) is unclear. This study investigated the relationship between the duration of drug holidays and prognosis after DTX therapy. This study retrospectively assessed 26 patients treated with DTX in our hospital. Overall survival duration was significantly longer in the long-term withdrawal group (duration of drug holidays ≥6 months) than in the short-term withdrawal group (duration of drug holidays ＜6 months) (P＝0.015). Similarly, progression-free survival duration was significantly longer in the long-term withdrawal group than in the short-term withdrawal group (P＝0.008). The short-term withdrawal group had a significantly lower body mass index (P＝0.009) and higher prostate-specific antigen (PSA) (P＝0.017) at the initiation of DTX therapy, higher PSA nadir during DTX therapy (P＝0.009), and higher PSA at the end of DTX therapy (P＝0.022), compared to the long-term withdrawal group. This study suggests that the optimal opportunity to introduce DXT therapy is when the patients with CRPC are physically able to tolerate chemotherapy and their tumor volume remains a lower burden. This may provide a clinical benefit, longer drug holidays, and a better prognosis.