Taurocholate binding to rat serum albumin was studied by equilibrium dialysis. The bile salt-protein interaction was studied under different experimental conditions with respect to temperature; ionic strength; Cl- concentration; pH and the presence of butanol in the medium. The results obtained suggest the existence of two binding sites for taurocholate on the albumin molecule, and indicate that both electrostatic and hydrophobic interaction play a role in the binding process.