To determine the validity of the hypothesis of assimilation or precipitation of cholesterol by Bifidobacterium species, resting cell assays and cultures were undertaken in TPY medium containing oxgall. With resting cell assays (pH 5), cholesterol was precipitated and redissolved in phosphate buffer (pH 7). At the end of the cultures, only part of the removed cholesterol from the culture medium was found in the phosphate buffer, while the missing cholesterol was in cell extracts. It appeared that removal of cholesterol during culturing was not solely due to its precipitation. It is concluded that growing bifidobacteria cells are able to remove cholesterol both by precipitation and assimilation.