Non-alcoholic fatty liver disease (NAFLD) has been reported to be helpful to identify high-risk individuals of developing prostate cancer. Our aim is to investigate the relationship between NAFLD and biochemical recurrence in metastatic prostate cancer patients. We retrospectively investigated 602 patients with metastatic prostate cancer receiving the androgen deprivation therapy. Liver fat was estimated with liver-to-spleen ratio by computed tomography (CT) scans. The relationship between NAFLD and biochemical recurrence was investigated with Cox models. The model for biochemical recurrence was adjusted for multiple variables. NAFLD was significantly associated with biochemical recurrence in patients with Gleason score ≥4+3 when adjusting for each of body mass index (hazards ratio [HR]=1.38; 95% confidence interval [CI]=1.08-1.77; p=0.01), visceral adipose tissue (HR=1.36; 95% CI=1.07-1.74; p=0.01), hypertension (HR=1.41; 95% CI=1.10-1.80; p=0.01), and diabetes mellitus (HR=1.42; 95% CI=1.11-1.82; p=0.01), using age and prostate-specific antigen level as potential confounder. The 2-year biochemical recurrence rate in the Gleason score ≥4+3 patients with and without NAFLD was 84.0% (100/119) and 72.2% (130/180), respectively (p=0.018). The median biochemical recurrence free survival of the Gleason score ≥4+3 patients with and without NAFLD were 17 and 21 months, respectively (p=0.005). NAFLD is an independent risk factor for biochemical recurrence in patients with high-grade metastatic prostate cancer. If validated in prospective studies, future research should test whether treatment of NAFLD can lead to better prognosis.