The bile acid content of the human gallbladder obtained postmortem from 30 subjects was studied. The principal components were found to be cholic, deoxycholic and chenodeoxycholic acids. Deoxycholic acid was notably absent from the bile of infants and some children, a matter which has been recognized earlier. Ursodeoxycholic acid was found in 4 specimens obtained from subjects 8 years of age or younger. A particular quest for 3[beta]-hydroxy bile acids in early life was fruitless. This latter species clearly does not constitute a significant portion of bile in early human life despite the recognition of similar species of adrenal steroids at this time. Methods have been described for the relatively simple measurement of bile acids by densitometry on paper chromatograms. A useful characteristic of chenodeoxycholic acid, when treated with acetic-sulfuric acid reagent, has been detailed.