Curly or kinky human hair is permanently relaxed into a relatively smoothed or S-curved condition by a series of treatments involving application of a non-injurious composition containing a water solution of a salt of a weak acid to disrupt internal bonds of the hair, while manipulating and straightening the hair, then removing and replacing the first composition with a fixative to reconstruct or modify the structure of the hair, and finally applying a stabilizing composition which also acts to set and condition the hair.