OBJECTIVE Docetaxel-based chemotherapy against castration-resistant prostate cancer (CRPC) has recently been shown to be effective and tolerable. The objective of this study was to retrospectively evaluate the efficacy and toxicity of low-dose docetaxel in combination with dexamethasone. METHODS Thirty-seven CRPC patients were administered a treatment regimen consisting of 50 mg/m2 docetaxel once every 3-4 weeks and 1 mg dexamethasone daily at our institution, between November 2004 and April 2014. RESULTS Twenty-four patients (65%) had a decrease in serum prostate-specific antigen (PSA) >50%. The median overall survival (OS) and PSA progression-free survival were 26.2 and 10.0 months, respectively. Ten of 12 patients (83%) taking analgesic agents reduced their intake because of decreased pain levels. Grade 3 febrile neutropenia occurred in 2 patients (5%). Nonhematological toxicities were less frequent but sometimes severe. Treatment-related death occurred in 2 octogenarian patients, 1 due to gastric bleeding and the other due to infective endocarditis. CONCLUSIONS Low-dose docetaxel in combination with dexamethasone is feasible in Japanese CRPC patients. Hematological toxicity is less than that seen with standard docetaxel therapy, but it is necessary to monitor patients for severe nonhematological toxicities, particularly very elderly patients.