Summary Background Serum vitamin D levels are associated with bone complications in patients with primary biliary cirrhosis (PBC). Increasing evidence suggests a nonskeletal role of vitamin D in various autoimmune and liver diseases. Aim To investigate the clinical relevance of vitamin D levels in PBC, especially their association with the therapeutic effects of ursodeoxycholic acid (UDCA). Methods Consecutive PBC patients were retrospectively reviewed. 25‐hydroxyvitamin D 25(OH)D levels were determined in frozen serum samples collected before initiation of UDCA treatment. Response to UDCA was evaluated by Paris‐I and Barcelona criteria. Logistic regressions were performed to identify the treatment response‐associated parameters. Results Among 98 patients, the mean serum 25(OH)D concentration was 17.9 ± 7.6 ng/mL. 25(OH)D levels decreased with increasing histological stage (P = 0.029) and were negatively correlated with bilirubin and alkaline phosphatase levels. After 1 year of UDCA therapy, 31 patients failed to achieve complete response according to Paris‐I criteria. The baseline 25(OH)D level was significantly lower in nonresponders (14.8 ± 6.4 vs. 19.3 ± 7.6 ng/mL, P = 0.005). Vitamin D deficiency at baseline was associated with an increased risk of incomplete response independent of advanced stages (OR = 3.93, 95% CI = 1.02–15.19, P = 0.047). Similar results were obtained when biochemical response was evaluated by Barcelona criteria. Furthermore, 25(OH)D levels were lower in patients who subsequently suffered death or liver transplantation (12.1 ± 4.6 vs. 18.4 ± 7.6 ng/mL, P = 0.023). Conclusions 25(OH)D level is associated with biochemical and histological features in PBC. Pre‐treatment vitamin D status is independently related to subsequent response to UDCA. Our results suggest that vitamin D status may have important clinical significance in PBC.