Myelin basic protein (MBP) was purified from guinea pig spinal-cord in a native-like form retaining the binding to all the myelin lipids. Since the guinea pig MBP was found to be much more labile than the corresponding MBP from bovine brain, the original procedure based on the use of hydroxyapatite and detergents was slightly modified as reported here. The product of this purification, lipid-bound MBP, may represent an alternative to lipid-free MBP for the induction, the study and the treatment of experimental allergic encephalomyelitis.