Abstract: Four samples of natural ox gallstone and seven samples of cultured ox gallstone were observed and compared by scanning electron microscopy. The four natural. ox gallstones showed a special porous strueture. Through analysis of the content of bilirubin (BR), cholic acid (CA), deoxycholic acid (DA) and cholesterol (CS) present in these ox-gallstones, the similarity of the cultured ox-gallstone to the natural ones was found to be proportional to the content of bilirubin and inversely proportional to the content of cholic acid and deoxycholic acid. this relation can be expressed by the bilirubin ratio BR/(CA+DA).