['End-stage chronic liver disease is associated with vitamin D deficiency but the prevalence across a broad-spectrum of liver disease is unknown. This study prospectively examines prevalence of vitamin D deficiency and response to replacement in chronic liver disease.', 'One hundred and fifty-eight outpatients with chronic liver disease were enrolled. Serum 25-hydroxyvitamin D (25[OH]D) levels were classified as: severely deficient less than 25 nmol/l, deficient 25-54 nmol/l or replete greater than 54 nmol/l. Sixty-five of 158 (41%) had cirrhosis.', '25[OH]D was suboptimal in 101/158 (64%), including severe deficiency in 24 patients (15%). Vitamin D deficiency occurred in liver disease of all aetiologies, including patients with only mild liver disease. 25[OH]D increased by 60.0% (19.11 ± 13.20 nmol/l) in patients with deficiency after vitamin D replacement and decreased by 25.2% (-18.33 ± 12.02 nmol/l) in non-treated initially replete patients over a median of 4 months.'] Is oral vitamin D replacement effective in chronic liver disease?