For many years Trichologists have been searching for a simple, non-invasive method to quantitatively evaluate hair loss and hair growth, like the hair pull test and wash test. Particular qualities and defects characterize both of these techniques. The standrard and unit area trichogram is a semi-invasive technique of greater help to the clinician in the evaluation of alopecia, but poorly tolerated by the patient. With a time going by and modern technology development, a new trichogram tecnique called the phototrichogram was developed. It is a noninvasive technique that allows the in vivo study of the hair growth cycle. It can be used to understand the rate of hair growth, the size of hair fibers, the frequency of Telogen hair follicles, and the quantification of shed hair. At its most basics, an area of the scalp, say a centimeter in diameter, is shaven and macroscopic pictures are taken. A second set of pictures of the same shaved areas are taken five days later. By comparing the first picture to the picture 5 days later the Trichologist can see which hair fibers have not grown (those hair follicles are in Telogen), which hair fibers have grown (those hair follicles are in Anagen), the rate of hair growth (how much longer the growing hair fibers are after 5 days), the density of the hair in the area photographed (the number of hairs in the photograph) , and if the Trichologist is really good, he/she can match up the photographs exactly and see which hair fibers are missing 5 days later, this gives an indication of the rate of hair shedding. In clinical research studies, especially those testing new hair loss treatments, an additional step is taken. Volunteers in the study have a dot tattooed on their scalp in the area of hair of interest. This spot is shaved at the start and examined for hair growth parameters, but the tattoo allows the Trichologists running the study to come back to the same spot after several months or even years to do another phototrichogram evaluation. In this way, Trichologists can produce a detailed quantitative evaluation of hair growth in exactly the same spot on the scalp over a long term study period and build up a good idea of what a treatment can do for hair growth in long term. Tattoos are not commonly used as people do not like much the idea. However, the tattoos used are usually an orange to red color that is barely visible, the tattoo is literally a little dot and can be removed with a laser or by biopsy later on if wanted.