Eleven patients with primary biliary cirrhosis were surveyed for evidence of vitamin A and zinc deficiencies. Vitamin A deficiency manifested as a low serum vitamin A concentration and abnormal dark adaptation was present in 9 of the 11 patients. A low serum zinc level was present in four patients who were also vitamin A deficient. All seven patients who received p.o. vitamin A therapy with 25,000 to 50,000 units per day for 4 to 12 weeks achieved normal vitamin A levels. Normalization of serum vitamin A was associated with significant improvement in dark adaptation (p < 0.01). In three patients, normalization of serum vitamin A level did not correct the abnormal dark adaptation. These three patients also had decreased serum zinc levels and dark adaptation abnormalities were corrected following p.o. zinc supplementation. These studies suggest high dose and long term p.o. vitamin A and zinc therapy may be required to correct abnormalities in dark adaptation in patients with primary biliary cirrhosis.