Porosity, elasticity, and texture influence the hair's ability to be changed. The types of color--temporary, gradual, natural, semipermanent, and permanent--depend upon the size of the "coloring" molecule to determine whether they penetrate the cortex (permanent) or precipitate on the cuticle. Different types of hair--thick or coarse, fine or thin--have varying affinity for different products and coloring/waving methods. Damaged hair is treated differently from hair with healthy, less porous shafts. Because so many people have color-treated hair today, dermatologists should be aware of all the latest changes and improvements, in order to assist patients with damaged or congenitally deformed hair. Acid-based permanents are becoming the most commonly used. Daily care with shampooing and conditioning has attained its most sophisticated level with the use of anionic and cationic surfactants in all hair-care products. It is also important for the dermatologist to be aware of what help is available for his or her patients. Cosmetic companies are eager to help any patient with severe problems with texture, dullness, over-fine or congenitally defective hair. The physician should send the patient with a severe problem directly to the nearest company headquarters or major city office to have a hair analysis, and receive suggestions from the experts of that company. For patients with moderate to mild problems, the dermatologist should be able to recommend three or four good salons in the local area with which he or she is familiar. Our main goal as physicians is to take care of the entire patient and to enable him or her to have a good self-image.